


this is the room one afternoon (I knew I could love you)

by PinkGerberDaisies



Category: Life with Derek
Genre: Accidental Voyeurism, Angst, Awkward Encounters, F/M, Fluff, Sharing a Bed, Smut, but as usual the plot got away from me, confession of feelings, presumed unrequited feelings, this was supposed to be porn without plot
Language: English
Status: Completed
Published: 2021-02-14
Updated: 2021-02-28
Packaged: 2021-03-14 05:47:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 25,634
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29413626
Author URL: https://archiveofourown.org/users/PinkGerberDaisies/pseuds/PinkGerberDaisies
Summary: "The woman looks like her. Like her. Casey McDonald. Not just similar, but practically a doppelgänger. From her long light-brown hair to her blue eyes to the shape of her nose and curve of her lips.He’s touching himself to a woman who looks like her."A short story in which Casey accidentally walks in on Derek in a compromising position and it changes the course of their entire relationship.Title comes from "the king of carrot flowers – pt. one" by neutral milk hotel
Relationships: Casey McDonald/Derek Venturi
Comments: 66
Kudos: 131





	1. one

**Author's Note:**

  * For [falsettodrop](https://archiveofourown.org/users/falsettodrop/gifts).

**Notes for the Chapter:**

> This plot was originally discussed with a friend as far back as 2019, but I'm the worst and it's taken me forever to actually sit down and write it. 
> 
> C - I'm sorry for the wait. I hope this story is worth it. I'm posting the first chapter now so that I'll actually have to commit to finishing it and can't flake on you again. Love you! Happy Valentine's Day!  
> \- Daisy

** one. **

“I was going to ask her to see the new Paranormal Activity sequel with me, but I don’t know – is that too obvious?” Lizzie lets out a frustrated huff on the other end of the phone, and Casey can perfectly picture her younger sister reaching to play with the long brown hair that’s no longer there. She’d warned Lizzie when she’d first brought up the idea of getting a pixie cut that she wouldn’t know what to do with her hands, but had Lizzie listened? Of course not.

“I think it sounds perfect.” Casey punches in the five-digit sequence for the door to her apartment building, shoving her shoulder against the glass when it jams halfway open. The lobby smells like old carpet and stale coffee and Jennifer in apartment two's pasta primavera, and she scrunches up her nose and adjusts her cell phone between her cheek and shoulder. “It’s not obvious, if you get too nervous you can pass it off as just hanging out.”

“You think I’m gonna chicken out?!”

“No!” Casey attempts to dig the tiny mail key out from inside her gym bag, fumbling for it inside the special compartment she uses to keep it safe along with her wallet and chapstick, her phone slipping precariously off her shoulder. “No – crap, stupid freaking lock –“ The unladylike grunts coming out of her mouth as she struggles with the eighty year old metal mailbox would be embarrassing if she weren’t alone in the lobby, but as it is she just finished an intense hour of dance class and she’s past the point of caring either way. “I’m just saying it’ll be a good chance to gauge her response. Hopefully, she’ll show some sign that she feels the same way.”

Lizzie hums noncommittedly. “I tried asking Edwin, but he met his girlfriend at math club so he’s not exactly Casanova. Should I ask Derek?”

“Do _not_ ask Derek.” Casey slams the mailbox closed, a move she’ll no doubt regret when it’s twice as hard to open tomorrow, and shoves the letters and cardstock junk advertisements into her bag before trudging up the stairs. Most of the time living on the fourth floor is nice, when the weather is good and the view stretches out over to Lake Ontario and she can drink her morning coffee and listen to the birds before the morning traffic gets bad, but today she curses every step of the ancient building. Her thighs are _burning._

“But he’s got more experience than anyone I know! You want up?” The sound of Simon babbling interrupts their call, and Casey manages to smile despite her exhaustion. Their littlest brother has always shared a special bond with Lizzie, and while teenage Casey would have been jealous about that, adult Casey tries to be more understanding. Lizzie is with him 24/7 and she isn't - it's only natural. 

“Ugh. Don’t remind me about Derek. I’ve had to live with that experience for the last year and a half.”

“Why did you choose to live with him – no, Simon, earrings aren’t toys - then?” Lizzie asks the same question she’s been asking every month since Casey and Derek made the announcement they were moving in together (not _together,_ of course, just sharing rent money – not that anyone would have any reason to accuse them of the other thing), and Casey rolls her eyes.

“Budget cuts.” She quips. “Why don’t you just do what _Lizzie_ would do?”

Lizzie snorts, which makes Simon giggle, so she does it a couple more times before answering. “Because _Lizzie_ is only confident kicking a ball around a muddy field or kicking ass on a Tae Kwon Do mat.”

“So, channel that version when you’re on your date,” Casey suggests, before promptly tripping over her neighbor’s doormat for the hundredth time (she would kill Joel if he didn’t make the best banana bread she’s ever tasted), “You know – minus the wrestling.”

“I feel like Derek would make some sort of dirty joke there.” Lizzie’s smirk is practically audible, and looks a little too much like Derek in her head, and Casey groans.

He absolutely would.

“All the more reason not to ask his opinion.”

“Speaking of – when are you guys planning on getting here?”

Casey pauses to read the note taped to her front door inviting her a Derek to the building Thanksgiving dinner on Monday if they don’t have other plans, and she smiles with a twinge of regret. She’ll have to bake a pie and leave it with Joel to take, since they won’t be here to participate. “Derek wants to leave early on Friday and I only have one class in the morning, so we should get there sometime in the early afternoon.”

“Good. Then you’ll be here in time to help me pick out an outfit for my maybe-date.”

“Of course! I wouldn’t miss it.”

There’s clamoring on Lizzie’s end and the sound of Simon saying something before a loud thunk and the call drops, and Casey laughs quietly to herself while shaking her head. That kid might be half McDonald, but his Venturi genes run strong. Clearly he had grown tired of sharing Lizzie's attention. 

Slipping her phone into her bag, she moves to unlock the door – already dreaming of the hot shower waiting for her on the other side. This key slides easily into the lock, the shiny deadbolt being the only new thing in the building and something Casey had insisted on when Derek had found this place, and she pushes the door open and drops her bag on the table with a sigh. Immediately heading for the fridge to get a glass of cold water and the ingredients for her favorite green smoothie.

 _First take care of your muscles, Casey,_ she reminds herself, _then you can indulge in a long shower._

It’s late in the afternoon, so the chances of Derek being home are slim, and she intends to take full advantage of having the place to herself. She got all her homework for the week done early in preparation for the holiday weekend, so she fully intends to treat herself by ordering Indian from the shop around the corner and watching _Pride & Prejudice _again. She’d tried watching it the night before with Derek to disastrous effect. The attempt had ended after approximately fifteen minutes and three disparaging comments about Darcy’s looks.

 _“Why would Lizzie ever go for this guy? I mean, Kiera Knightley is a solid ten, and I’m supposed to believe she’s attracted to this guy?_ This _guy, Casey?”_

The ensuing argument had been heated, to say the least, and she’d been so irritated by his triumphant smirk when she’d let him switch the TV over to hockey that she’d locked herself in her room and written the first draft of an essay that isn’t due for another three weeks out of frustration.

_“Looks aren’t everything Derek, and besides, Darcy IS attractive!”_

_“Are you saying you’re seriously attracted to this guy?”_

_“Stop calling him ‘this guy’! Besides, everyone is attracted to him. He’s Mr. Darcy.”_

_“Then you should go for someone different. Branch out and try something new.”_

Psh. As if she wants to try something new. His version of new would probably be the exact opposite of the men she’s dated, just to trick her into going to a monster truck rally or something. She’s perfectly happy with wanting her fairytale romance, dashing hero and all, thank you. Even if finding said romantic hero has proven to be more difficult than fifteen-year-old Casey had once thought.

“Why did you choose to live with him?” Lizzie’s question comes echoing back, and Casey shrugs to the empty kitchen.

It's complicated. 

What she’d told Lizzie, and subsequently their entire family for the last two years, was true. It _is_ cheaper for two college kids to share a place than to pay two separate rent checks in a popular college town like Kingston. Especially when their parents want to help, but can’t afford much with four other kids still at home. But the other reason, the one Casey refuses to admit out loud to anyone but herself, is that she’d _missed_ him. For all his obnoxious qualities – and he _is_ obnoxious – he’d made high school more interesting. Exciting. And when that was gone, she’d found some of the color had gone out of life as well.

She’d been shocked when Derek had announced his acceptance into Queen’s University (stealing her thunder in the process), but ultimately not as upset as she’d let on. The truth was, she’d actually felt kind of relieved not to be moving so far away from home by herself and had hoped having Derek along would mean she wouldn’t get as lonely. But they’d both wanted the full freshman experience and that meant living in the freshman dorms, so Derek had found a rowdy place with a bunch of boys who were also on the hockey team, and she had found a nice triple room in Victoria Hall, and her initial hope that the two of them might find opportunities to hang out was quickly buried underneath coursework and tests and new friends.

It wasn’t that she and Derek had _avoided_ each other, per se, they just… didn’t go out of their way to see each other. Ever. And once Casey realized he wasn’t going to make the first move towards friendship, she decided she _couldn’t_. If separation was what he wanted, then separation would be what he got.

Nobody had been surprised back home. “Of course you’d scatter the second you had the chance!” Lizzie had said. “Why would you _want_ to hang out with him? He drives you crazy!” She rarely saw him, except for those occasional times when she’d catch him lounging about and flirting with random girls in The Lazy Scholar, and when she did see him she refused to make eye-contact, lest he sense her weakness and use it against her to pull another prank.

Okay, maybe she also saw him at one or two hockey games, but that was purely at George’s request, who wanted to know how Derek was getting on in a tougher arena.

(Not that Derek had known about those games at the time, of course.)

But it’s true what they say – absence does make the, well, she won’t say heart because hearts and Derek don’t go together, nor does the word _fondness -_ but it does make you miss someone. Even the stupid things you used to hate. (The first time he’d called her keener on campus she’d nearly grinned and hugged him instead of picking a fight.) And while her roommates were great, she’d quickly discovered why living in a building with 900 people who all possess varying standards of cleanliness and academic commitment might not be the best situation for someone with a type-A personality. 

So when George and Nora had sat them down the next summer to talk finances and how they were going to manage paying for more expensive off-campus housing sophomore year, she’d been shocked, but not altogether displeased, when Derek had groaned and rubbed his hand over his face and begrudgingly suggested they share a place – with the obligatory overdramatic sighs about how he was sacrificing _so much_ by letting her cramp his style, and that she’d need to let him have the biggest room wherever they lived in compensation.

Casey had protested, of course, because that’s what was expected and it would have been strange and suspicious if she’d agreed right away. Not that there’s anything to be suspicious of, of course, just she and Derek have an MO to follow and the few times they did get along in high school it instantly made people _more_ concerned than when they were biting each other’s heads off. After the requisite number of complaints, though, she’d gone upstairs to start apartment hunting online – only to be shocked for the second time when two weeks later Derek said he’d found the perfect place in the Student Ghetto.

Perfect might be too strong a descriptor for this place, but it was within budget and had two rooms (he took the biggest, as promised, but let her have the one with the bigger closet) and wasn’t so small they were constantly on top of each other, and it got a good amount of sunlight so overall Casey was satisfied.

And somehow, despite the very real bets their siblings had wagered on the situation, they were both still satisfied enough to renew the contract for a second year. Satisfied and, dare she say, happy. It’s not perfect, but over time their fights have mellowed, they’ve gotten used to each other’s habits and schedules, and – disparaging remarks about literary heroes aside – they generally get along fine. Especially once he offered to cook dinner a few times a week in trade for her helping with his homework (she didn't even know he knew how to use a stove, but he'd proven to be a pretty good cook). 

It _works_ , and that’s enough to bring a small smile to Casey’s face as she finishes her water and draws the kitchen curtain to the side to admire the changing color of the leaves on the big elm tree outside. They’ve become friends. _Best_ friends, she might say if she’s in a particularly good mood and Derek’s been behaving. And she can honestly say she doesn’t regret moving in together one bit.

It’s quiet in the apartment – a nice sort of quiet that she finds relaxing after the upbeat tempos of her dance class – and she figures Derek must be out with one of his other friends or at practice. He’s rarely home after five, either busy with hockey or with dates - although, she realizes with some surprise, she hasn’t seen him with a girl in a while. Not since their disastrous double date a month ago. The one that started with Derek picking a fight and ended with Casey’s latest boyfriend, Arthur, dumping her. (“What a fucking dumbass,” Derek had said, offering no further elaboration.) Which is why she nearly jumps out of her skin when she hears him cry out her name.

Her glass clatters loudly in the sink (for once she’s grateful they settled for cheap plastic instead of splurging on nice glassware), carelessly discarded in her haste to make sure he’s not _dying_.

 _Honestly, Derek, what trouble have you got yourself into now_?

There’s no malice in the thought, though, she’s too worried for that, and she rounds the table and runs down the hallway towards his room without a moment’s pause - noticing the door already slightly ajar and not bothering to knock first like she normally would before pushing it open.

There’s no blood. No broken limbs. No sign of intrusion. And yet, what she sees will be seared in her mind forever.

Derek is sitting at his desk, legs splayed out in front of him, pants unbuckled, his hand wrapped around his length (she refuses to think _cock_ – the Derek in her head can’t have one of those), and his laptop screen is propped open to some rather vigorous, vocal porn.

Only, it’s not just any porn. While the lewd way the woman is draped over the man, his hips pistoning against hers, one hand rubbing furiously between her legs while the other plays with her breasts, would be enough to have Casey blushing for a month, that’s nothing compared to what she sees when the camera cuts to their flushed, sweaty faces and she finds her own image staring back at her.

The woman looks like her. Like _her._ Casey McDonald. Not just similar, but practically a doppelgänger. From her long light-brown hair to her blue eyes to the shape of her nose and curve of her lips.

He’s touching himself to a woman who looks like her.

Casey’s brain short-circuits, forced to default back to its base commands at the sudden lack of any higher thought processing ability, and she instinctually cries out his name. “Der- _ek_!”

His eyes fly open to find hers, but it’s too late – he comes hard, coating his hand and stomach with his orgasm – and Casey watches ( _god_ , why is she _watching_ ), wide-eyed, until he sags against his chair, utterly spent, before spinning on her heel and sprinting into the bathroom. Slamming the door shut and locking it behind her.

Derek just came. She just _watched_ Derek come.

"My room is off limits." It was one of the first things he'd ever told her. Why doesn't she ever listen? 

She sags against the wood, her chest heaving with every breath, and tries to ~~come to grips~~ understand what it is she just witnessed. Mentally working through the events of the last thirty seconds like it’s a question on an exam. Grasping at any stray wisps of logic she can find. 

One: Derek watches porn when she’s not home. Okay, that’s not surprising. It’s not like she doesn’t know how much he likes sex. He’s a sexually active adult – it’s only natural for him to want to ~~jerk off~~ ~~masturbate~~ _indulge_ himself sometimes. She can accept this.

Two: He does this little twist with his wrist when he –

_NO! No that is not number two!_

Two: Derek watches straight porn. That isn’t really significant, but it delays thinking of number –

Three: Derek watches porn involving a woman that looks like her.

Is this the first time he’s done it? Was it just a coincidence? Did he not notice the similarities – too caught up in her breasts or… other things to pay particular attention to her facial features? Or did he purposely go looking for - no. That's too much. It's not possible that he _chose_ that particular video because of that actress, is it?

Almost robotically, Casey pushes herself away from the door and starts preparing for her shower, methodically stripping off her still-sweaty sports bra and leggings and turning on the water – checking the temperature with her hand before stepping into the cramped space and closing the glass door behind her.

With the water pouring down around her and the steam fogging up the bathroom, encasing her in its safe bubble, she can’t help but ask the one question she’d wanted to avoid above all else.

Why would Derek _want_ to watch someone that looks like her?

 _No,_ she shuts that thought down hard, _don’t go there. That’s the danger zone._ That’s the line of thinking she swore to herself when they moved in together that she’d never go down. Nothing good can come of contemplating anything like that regarding Derek.

_He’s your step-brother. Your step-brother. Your step-brother._

_Casey_. She can still hear him. How he’d said her name in a way he’s never said it before. The way he’d _moaned –_ almost pleading.

Heat pools low in her belly, sparks tingling from her head to her toes, and Casey scrambles for the shampoo, squeezing out way too much and making a mess, but not really caring. Working it into a lather on her scalp with almost too much pressure.

_He’s your step-brother. He’s off limits._

Except, he hasn’t been just her step-brother for a long time. If he ever was _just_ that at all.

Her hands fall, trailing along her collarbones, dipping lower, before she realizes what she’s doing and snatches them back – turning around to rinse out her hair instead. (Instead of what, she doesn’t dare consider.)

Unbidden, the image of Derek’s face as he’d fallen into ecstasy comes to mind – the way his hand had clenched around himself, his breath hitching - and Casey shivers and involuntarily clenches her thighs together.

 _No!_ She berates herself. _Watching him was a violation of his privacy and what you did was wrong, Casey McDonald! You’ve never thought about him like that before, you aren’t allowed to now!_

Okay... so maybe that's not entirely true. She has thought about Derek and… and his _cock_ okay, she'll admit it. But it’s not her fault! Sometimes after a shower he’ll step out of the bathroom with his towel slung low around his hips – low enough that she can see the V there and the happy trail leading down down _down_ – and she’ll be just exiting her bedroom which is INNOCENTLY located across the hall from the bathroom and catch him like that. Water droplets still clinging to his freckled shoulders. And in those moments, her brain, which is an entity unto itself sometimes and also living inside the body of a healthy, red-blooded twenty-year-old woman, will sometimes dare to imagine what might be hidden underneath Derek’s towel.

But she’s never _done_ anything with those thoughts! She’s certainly never gone to the internet in search of a man that looks like him to touch herself to. She’s never even watched porn at all – preferring to get her fill from trashy romance novels she picks up at the secondhand bookstore around the corner. (If she gravitates towards covers with smirking, curly-haired brunette men, well that’s purely a coincidence.) She likes a little more plot and foreplay and actual characterization – something she’s sure Derek would tease her for. “You’re such a keener, Space Case, of course you want to _work_ for your orgasm.” 

NOT that she’s ever discussed orgasms with Derek!

(Why oh why does his voice seem to live inside her head!?)

Finished with the shampoo, Casey reached for the conditioner and starts working it into the ends of her hair first – trying hard _not_ to think about how Derek had told her just three days ago that he liked the smell. A sudden, unexpected compliment that had left her speechless and staring at him as he casually reached for another slice of pizza.

His hair products are there, too, on the shelf next to hers, a thought that gives her pause. It’s so… domestic. When did they become domestic? When did she start trusting him not to mess with her toiletries? When did he _stop?_

Why would Derek _want_ to watch someone that looks like her?

There’s that question again, and Casey tears her gaze away from the bottles to finish what she’s doing. She can’t hide in here forever – pruney skin aside, the water would go cold eventually and no amount of embarrassment is worth that kind of suffering – but she has no clue what she’s going to say to Derek when she sees him. Or what he’ll say to her.

Will he laugh? Write it off as a joke? Apologize? She honestly has no idea. This is unprecedented ground for them, and while Derek usually avoids serious emotions or conversations like the plague, surely _this_ one he won’t be able to casually shrug off like he does everything else, right?

They’ll have to talk about it. She needs to apologize for walking in on him, at least, and she needs to know ~~why~~ … she just… she needs some answers.

She rinses out the conditioner and quickly goes over her body with her body wash and loofa, refusing to linger anywhere too long on her oversensitive skin, before turning off the water and stepping out onto the bathmat. Grabbing her towel, she pats herself dry and wraps it around her body, fixing it securely underneath her armpits. 

The mirror is too steamy to see herself properly, for which Casey is grateful (how is she ever going to be able to look at her own face again?), and she stands there for a moment in the humid bathroom practicing the breathing techniques she’s learned from so many mornings spent doing yoga in their living room. 

She can do this. It doesn’t have to be a big deal if they don’t make it one. _Deep breaths, Casey._

She can do this.

But by the time she’s dried and dressed and ready to face what may be a life-altering conversation, he’s gone.

**Notes for the Chapter:**

> Would you believe this was supposed to be a oneshot? Laughing that I ever thought I could keep it reasonably short.


	2. two

**Summary for the Chapter:**

> The boat ya you know she's rockin' it  
> And the truth well ya know there's no stoppin' it
> 
> \- The Denial Twist, The White Stripes

** two. **

Silence.

It’s pervasive.

And not the serene silence of yesterday afternoon, no, that would at least allow her to keep sleeping or maybe get some extra credit work done before class or practice the meditation exercises her therapist had suggested. This silence is heavy. Loaded. Like the dreaded moment when you cease to hear the whistling of the bomb right before it drops on your head. This silence has her clutching her duvet underneath her chin and reminding her muscles to relax after they tense up at every single creak in the old apartment building.

He hadn’t come back.

She’d waited for him, of course. Seated primly at the edge of the couch for a solid five minutes before shooting to her feet and pacing back and forth for another hour – eyes glued to the front door. No doubt leaving an indentation in the hardwood that will be traceable for the next sixty years’ worth of occupants.

_And here, students, is where Casey McDonald waited for Derek Venturi to explain why he’d been masturbating to her pornstar doppelganger. It’s also where Casey McDonald eventually died of hunger when he failed to return – having absconded to Timbuktu, never to be seen or heard from again. The rent is $1,000 a month – interested?_

Eventually her stomach had grumbled loud enough to interrupt the persnickety future landlady in her head – angrily reminding her that she hadn’t eaten since the green salad she’d had for lunch and nearly making her jump out of her skin at the sudden sound - and that had put an end to her pacing for the night.

She’d eaten dinner, absentmindedly watched the news, then kept the TV on through re-runs of _The_ _Mike Bullard Show_ , before finally giving up around one in the morning and accepting that wherever Derek was, he wasn’t coming home anytime soon, and she might as well head to bed. They could deal with their important conversation tomorrow after a good night’s sleep and a chance to develop a sense of humor about the whole incident. (Which she’s certain will happen – after all, it was only an innocent mistake, right? They’re friends. They can laugh about this. Probably.)

Only, her subconscious apparently had other ideas because the second her eyes had closed, she’d slipped into a very vivid (haunting, not at all pleasant) dream involving a beach, her favorite bikini, ice cream, and a fully nude Derek.

But she’s totally going to be able to laugh about this someday.

Definitely.

Which is how she’d ended up here – tucked in bed at five a.m. and staring up at the dancing shadows on the ceiling – anxiously trying to determine if each little noise could be Derek’s footsteps in the hall, or if they’re simply the normal sounds a building makes at night when it “settles.”

Of course, she could just get out of bed and _check_ if he’s home. It wouldn’t be the first time she’d woken him up early in the midst of having what he likes to call a Certified Crazy Spacey Extravaganza. Only those usually only happen during mid-terms or finals week and he’s usually the one bringing her back from the edge of a complete meltdown, not the cause of it.

_Hey, Der, could we do that thing we do sometimes when one of us is having a bad night? But like…_ after _you explain what on earth happened yesterday?_

Somehow, she doesn’t think he’d simply offer up a reasonable excuse and everything would magically be fine between them.

Sighing, she reaches blindly for her phone – dismissing the notification on the front reminding her that it’s currently set to Do Not Disturb and she _should_ be working on getting her solid eight hours – and brings up the default browser. It’s got a crappy connection and she’ll regret using up the data when her bill comes at the end of the month, but it’ll have to do right now. If she gets out of bed and turns on her laptop that would really mean admitting defeat, and she isn’t that far gone yet.

Eventually the Google search bar pops up and she types in the first thing that comes to mind.

**How to talk to your stepbrother about any latent feelings of attraction he may be experiencing towards you.**

Not the best question she’s ever come up with, but hey – there aren’t really rule books for dealing with this sort of thing. If there were, she would have read them all by now.

A few links start to slowly load, the entire page showing up in agonizing increments, but most of them are focused on various inapplicable psychology articles discussing latent thoughts, so she dismisses them and decides to try again.

**Walked in on stepbrother in compromising position – what to do.**

That one immediately brings up some decidedly adult-rated answers, and Casey flushes scarlet and quickly exits out of the browser before tossing her phone back on her nightstand like she’s been burned. Her mom had been right when she’d told them nothing good came from using the internet after midnight.

There’s _porn_ out there about stepsiblings. A _lot_ of porn.

( ~~Does Derek watch that, too?)~~

Apparently, she’d been very naïve when she watched _Clueless_ as a kid and assumed that situation was the anomaly, not the norm. ( _I mean, who could resist Paul Rudd’s charm? Cher gets a pass.)_ Are stepsiblings just out there in the world hooking up every day like it’s no big deal? She’d thought... well she’d always assumed _some_ parents would frown on that kind of thing. That it would be the equivalent of assassinating an archduke and starting a World War or nailing a list of ninety-five religious complaints on a church door. Life-altering, family-imploding, chaos of the highest order. The kind of thing friends would find sick and twisted and that might make a normally loving, doting mother horrified or extremely disappointed. Or both. Even if said stepsiblings hadn’t met until they were older and never viewed each other as proper siblings, even when they tried.

(And oh, how she tried. In those rare moments in high school when Derek had been… almost kind. Dropping everything to save her from the Truman situation in Toronto, taking her to prom, calling her Dad and making him come back to London to spend time with her, dancing with her in that competition. In those moments she had _tried_ to think, “he’s such a good brother,” but the thought would curdle like old milk every time.)

_You’re such an annoying brother._

_Stepbrother._

_Same difference._

Yeah, right. It wasn’t the same difference at all and saying it out loud hadn’t changed anything. She’ll never be able to see him the same way she sees Edwin. Especially not now.

If Derek is _potentially_ (and she’s not saying that he is) fantasizing about her, that might mean he doesn’t find the idea of stepsiblings having feelings for one another entirely vomit-inducing, which also might mean he finds her… attractive… possibly. And if he does find her attractive, what does that mean for their ~~relationship~~ friendship?

What does she want it to mean?

“Urgh!” She throws her hands up to the empty room and rolls over onto her stomach to bury her face in the pillow. She can’t go there right now. Not when Derek’s disappeared and it’s the middle of the night and she isn’t any closer to getting answers from him than she was ten hours ago. There’s no point opening that can of worms until she knows what kind of Derek-worms she’s dealing with.

Ew. _Gross_. She’ll come up with a better metaphor in the morning, too, after she’s had a few more hours of sleep and can think properly.

With another groan, she reaches for her iPod and turns on her favorite classical playlist. Drowning out her merry-go-round of thoughts with Vivaldi and Dvorak and starting her relaxation process by focusing on her fingers and toes, then the rest of her body piece by piece.

Nighttime always makes everything more confusing. That’s all this is. She’s overtired and probably still in shock. A few more hours of sleep and she’ll be back to being the version of Casey who definitely doesn’t have feelings for Derek and definitely isn’t affected by what she saw.

Definitely.

****

It turns out Derek is much better at avoiding confrontation than she’d thought. In the past three days he’d managed to be awake before she was (a sign of the oncoming apocalypse, she’s sure) and get home after she’d fallen asleep – despite her best efforts to stay up later and later in the hope of catching him. The only way she knew he’d come back to the apartment at all was the growing pile of laundry in his hamper and her dinner leftovers missing from the fridge each morning.

She’d almost expected him to grab the Prince and drive back to London on Friday without her, leaving her to the mercies of the student carpool bulletin board on campus, but to her surprise (and relief – the carpool board and its list of strangers intimidates her) he’d texted her after her morning class ended to say he was packed and waiting for her in the parking lot and could she please _hurry._

Which is how they’d ended up here. Him, fiddling with the CD controls so that he can sing along with the White Stripes, and her, trying to pretend she _isn’t_ staring his hands and desperately trying to come up with something to say. (Have they always been like that? So broad and masculine and capable-looking? Nails neatly trimmed and fingertips calloused from playing guitar. Hands that could -)

“So,” She starts, awkwardly clearing her throat and glancing at his face out of the corner of her eye, “What have you been up to the past few days?”

Derek’s hand flies back to the knob on the dash and suddenly the volume is deafening – a cacophony of electric guitar and drums – and Casey winces hard enough that he takes sympathy on her and turns it back down. Not all the way, but enough that she hopefully won’t have a migraine by the time they reach London.

Message received.

If this were any other occasion, any other situation, any other day, Casey wouldn’t hesitate to turn off the music, twist around in her seat, and demand they talk about this. She’d have a bulleted list of talking points and counterpoints and wouldn’t back down until she got what she wanted. But the more she looks at the grim set of his mouth and the crease between his eyebrows and the way his right hand keeps flexing on his thigh while the fingers on his left tap discordantly against the steering wheel, the more she loses her nerve.

Maybe… maybe they _shouldn’t_ have this conversation in a cramped car driving down the 401. It’s a delicate situation. One that requires cautious unpacking and careful handling in a safe and secure location that’s free from things that might kill them should Derek take his eyes off the road or decide barrel-rolling out of a moving vehicle would be preferable to explaining his actions.

_God,_ she thinks, rubbing her temple, _I sound like I’m talking about some sort of fragile package._ Derek is anything but fragile. (Well, except where his mom is concerned, but she knows he tries not to let that show and so she’s never brought it up. It’s the least she can do, given her own complicated situation with her dad.) Derek is a whirlwind. A force to be reckoned with. He can handle hard things when he wants to.

Still – they won’t get anywhere if he starts the conversation already in a bad mood, so she might as well let it go until he seems more open to answering some of her questions. This is fine. They’ll focus on driving home and _then_ they can talk about what happened. No problem. She can wait.

(She’s not chickening out. She’s _not_. She’s just… waiting for a better venue. The opportune moment, as Jack Sparrow would say.)

Casey grabs a book out of her bag – it’s optional reading for one of her literature classes, but she’ll get extra credit if she submits an essay on it and every little bit helps – and settles in for the drive. Allowing the voices of Jack and Meg White to drown out her thoughts.

_If you think that a kiss is all in the lips_

_C’mon, you got it all wrong, man_

_And if you think that our dance was all in the hips_

_Oh well, then do the twist_

_If you think holding hands is all in the fingers_

_Grab hold of the soul where the memory lingers and_

_Make sure to never do it with the fingers_

_‘Cause I’ll tell everyone in the world_

_But he was thinking about the girl_

_Ya, but he’s thinking about the girl, oh_

****

“Thank god you’re here!” Lizzie starts dragging Casey by the arm into the house practically the second Derek puts the car in park, barely pausing long enough to get out of the way of the hurricane of squealing excitement that is Marti when she comes dashing out of the house to throw her arms around her favorite brother. “I’m having an outfit crisis. Simon got applesauce all over my first choice.”

“Nice to know I’m wanted.” Casey laughs. “Let me just grab my bag and then I’m all yours.”

“Here.” She turns to find Derek already behind her, one arm around Marti and the other shoving the handle of her suitcase so that it rolls over to her feet.

It’s the first word he’s spoken to her in days, and Casey hardly recognizes her own stilted, formal tone when she finds her voice and offers him a cautious reply. “Oh. Thank you.”

Derek shrugs before turning his full attention back to Marti. Cracking jokes about how much she’s grown in the two months since they’d last been home and teasing her about her bright purple Taylor Swift t-shirt. Even though everyone knows he’s let Marti play _Fearless_ for him more than once in its entirety. His love for Marti was Derek’s first (and, for a long time, _only_ ) redeeming quality, and Casey chuckles as she remembers that time she’d come home to find him covered in glittery make-up and wearing her clothes after allowing Marti to give him a makeover.

“What?” Derek shoots her a sharp glance when he hears her laughter, and she almost tells him her thoughts – eager to have his smile directed at her - but something about his expression has her clamming up.

“Nothing.”

“Whatever.” He rolls his eyes and fishes his car key back out of his pocket. “Come on, Smarti, let’s go get donuts. I’m starving.”

Casey watches as they climb back into the Prince, Marti talking a mile a minute about Taylor’s upcoming album release, and doesn’t take her eyes of them until the car has made it down the block and disappeared around the corner.

“Is something going on with you two?” Lizzie asks, eyes narrow and her hands propped on her hips, and Casey drops her gaze to her suitcase to hide the sudden inexplicable surge of guilt she feels. Like she and Derek have something to hide. Like they've done something irredeemably _wicked._

“No. Derek’s just being Derek.” Lizzie hums, but Casey can tell she isn’t convinced, and so she desperately attempts to change the subject before her sister can grill her anymore and force a confession. “Come on – let’s go upstairs. You’ve got a date to prepare for!”

Thankfully, the reminder of her impending big night snaps Lizzie out of whatever dubious thoughts she’d been having, because she straightens her spine and spins around to head back into the house. Allowing Casey enough time to take a few deep breaths and force any thoughts of Derek into the back of her mind.

“Her name is Katie. I’ve known her for a couple of years, but we’ve never really been in the same social circle until this year.” Casey motions for Lizzie to close her eyes, and she pauses long enough in her story to allow Casey to start applying eyeshadow. “She tried out for the soccer team and made it and I ended up sitting by her on the bus ride to play against Westminster and we really hit it off.”

“That’s exciting! Open.” Casey reaches for the mascara with a smile, handing it over to Lizzie to put on herself. “She sounds awesome, Liz, really. And we both know how amazing you are.” She playfully bumps Lizzie’s shoulder, laughing when her cheeks turn pink. “How could she _not_ like you?”

“Well, she could only like boys,” Lizzie replies practically, standing and heading over to the pile of clothes heaped on top of her bed and ruffling through them to hold up options for Casey's approval.

“Ugh. Boys are nothing but trouble. She’s better off without them.” Casey scrunches up her nose, thinking of one boy in particular who she can hear arguing with Edwin downstairs over whatever the latest video game is. “All they do is make your life confusing and distract you until your grades start to suffer.”

“Are you talking about Arthur?” Lizzie takes her hand with a sympathetic frown, and it takes Casey a solid five seconds to remember who Arthur even is.

“What?”

“What?”

“Why would I be talking about Arthur?” Her forehead wrinkles, and she tries to think what she could have said in the last two minutes to give her sister than impression. Arthur hadn’t been confusing. He’d been, well, _boring_. Something Derek had tried to tell her from the beginning, but she would never admit out of stubbornness and respect for him.

“I don’t know.” Lizzie shrugs. “You sounded… upset. I just assumed you were still hurting over the break-up.”

“Oh,” Casey practically giggles, waving her hand dismissively, “No. I’m not hurt about that. We only dated for a couple months and anybody who runs the first time they witness Derek and I having an argument probably can’t handle being in my life long-term.”

“I thought you and Derek didn’t fight that much anymore.” Lizzie tugs her t-shirt over her head and steps out of her sweatpants, trading them for the casual knee-length floral black dress Casey had suggested.

“Um…” She hesitates, fiddling with the sequins on one of Lizzie’s throw pillows, “Sometimes. I mean, you know us.”

“I guess…” Lizzie’s voice trails off, that suspicious look from earlier returning, and Casey crosses the room and grabs a maroon leather jacket out of the closet and tosses it in her face with a playful grin.

“Wear this over the dress. It’s cute and it’ll keep you warm.”

“Thanks.” Once again suitably distracted, Lizzie shrugs it on over her shoulders and does a little spin, holding out her arms. “Well? How do I look?”

For one brief moment, it’s staggering how grown-up Lizzie looks. With her pixie cut and make-up and fashionable outfit – all dolled up for a date. Wasn’t it just yesterday this room belonged to Casey and Lizzie was an awkward pre-teen whose biggest concern was whether or not she’d attend her city track and field finals and Casey’s biggest concern was prom? Where did the time go?

“You look perfect, Liz.” Casey smiles and pulls her sister in for a warm hug. “She’s gonna love you.”

Once Lizzie’s out the door and on her way to what will hopefully be a successful evening, Casey spends a good hour in the kitchen baking chocolate chip cookies with Simon’s help (or, perhaps, despite Simon’s interference) and catching up with her mother. They talk on the phone every Sunday night, but it’s different being able to chat in person – the casual laughter and jokes interspersed with Simon getting flour all over himself and stealing chocolate chips when he thinks they aren’t looking – and Casey basks in her mom’s warm presence and affection.

_If only I could ask for her advice regarding Derek_ , she thinks regretfully while scooping cookie dough onto the baking sheet in neat, perfectly round balls. If he were any other boy she wouldn’t hesitate (leaving the more graphic details out, of course). In the years since she left for university her relationship with her mom has matured a bit, to the point where Casey doesn’t really bat an eyelid at talking about her dating life or asking for advice on matters of sex and intimacy, but there’s absolutely no way she can tell her _mother_ about her convoluted emotions regarding Derek – and being vague about the _who_ she walked in on wouldn’t work when the only person she lives with is her stepbrother.

As if reading her thoughts, Nora bumps her shoulder against Casey’s and gives her a wide smile. “So, any new boys in your life lately?”

Willing herself not to blush, Casey casually lifts one shoulder and shakes her head. “Nope, not really.”

Nora grabs Simon’s hands before he can shove them into the mixing bowl, whirling him away from temptation when he scowls and handing him an apple slice instead (he’s never looked more Venturi than when he turns up his nose at the fruit). “What about that one you mentioned from your romantic literature class? Steve or Scott or something. That seems like the perfect setting for – what’s that term you like? – a ‘meet cute’.”

“Sean?” Casey looks up in surprise. She hasn’t thought about the cute red-haired guy who sits next to her in class in days. Honestly, she’d forgotten she’d even mentioned him to Nora at all. “He’s just a friend. More of an acquaintance, really. I’ve never spoken to him outside of class.”

“Well,” Nora bumps her shoulder again, conceding a few more chocolate chips to Simon, “Maybe you should change that.”

“You’re making cookies!?” Edwin bursts into the room before Casey can formulate a reply, bringing an overwhelming scent of bergamot and cinnamon along with him that makes her eyes water. His dark hair has been carefully gelled and styled and he’s got his favorite plaid button down on, and those things coupled with the cologne bath can only mean one thing. “You totally have to save some for me after I get home from my date.”

“Edwin!” Marti comes careening into the room after him, her fuzzy socks slipping on the kitchen floor. “You sprayed your perfume all over my toothbrush! It smells gross now!” She shoves the sparkly pink toothbrush straight at Edwin’s face, and if he hadn’t had a growth spurt over the summer, she definitely would have stabbed him in the nose.

“It’s not perfume.” He bats her hand away and rolls his eyes. “It’s _Le Male_. And McKenna loves it.”

“Then McKenna must not have a nose.” Marti pinches her nose between her thumb and forefinger, then sticks out her tongue. Pretending to vomit, too, just to really drive her point home.

Nora swoops in to intervene before the argument can get out of hand, and Casey has to hide her smile behind her hand.

It’s good to be home.

Derek wanders into the kitchen to investigate the commotion and, approximately five seconds later, determines Marti to be in the right and swats Edwin on the back of the head. “Dude, you smell like the inside of a Hollister. Buy Marti a new toothbrush.”

“A pink one.” Marti nods, folding her arms and leaning against Derek. Bolstered by his support and clearly feeling confident that she’s going to come out on top.

“A pink one.” Derek agrees seriously, and Edwin, despite all his protests over the past few years that since he moved out Derek can’t boss him around anymore, crumbles under the weighted stare of his older brother like he always has. 

“Fine,” He groans, throwing both hands up in surrender, “I’ll pick one up on my way home.”

“Thank you.” Satisfied, Marti jumps up to sit on the counter, swinging her feet happily, and Edwin rolls his eyes again and heads to grab his jacket off the hook by the back door.

“See you guys later. Case –“ He offers her his best doe-eyes, and she has to bite the inside of her cheek to keep from laughing at his sugary-sweet expression. “Promise you’ll save me some cookies. Yours are the best.”

“Of course I will, Ed.” She shoos him out the door, shaking her head fondly. “Go have fun with McKenna.”

“Can I have some cookie dough, Casey?” Marti perks up, using the exact same look as her brother and propping her chin on her hands. A pose that _could_ seem angelic, if Casey didn’t know Derek had trained Marti to use that particular move when she really wants something. Clearly the Venturis all went to the same school of cajoling while the McDonalds were busy learning manners. Will Simon be the same way? _Probably_ , Casey thinks with a rueful smile. Except with him it’s bound to be ten times worse since he’s the baby of the family. They all already spoil him rotten.

Still, Casey tries to stand her ground and set a good example. “No, Marti, you could get salmonella. You’ll have to wait until after they’ve finished baking.” 

She scrunches up her nose. “What’s salmonella?”

“It’s an excuse keeners use when they want to be lame.” Derek cuts in before Casey can answer, nudging Marti conspiratorially and whispering something in her ear.

_That can only mean trouble._

He saunters around the island to where Casey stands by the oven guarding the bowl, his intentions clear, and she watches him warily – trying to predict his next move.

“It’s not an excuse,” She argues, shifting a little to put herself between him and the still half-full bowl when he attempts to grab it from out behind her, “It’s a very real thing and people can get really sick from it.”

“Who?” He steps in closer, his eyes meeting hers for the first time since the _incident_ and refusing to look away, and Casey inhales sharply. _He_ doesn’t smell like the inside of a Hollister. He actually smells… kind of nice. Really nice. And have his eyes always been so brown? 

“Huh?”

“Who have you ever known to get sick from salmonella?” Derek demands, stepping slightly to the left, and Casey follows him without thinking.

“Well, um…”

“Exactly.” The corner of his mouth quirks up in that infuriating way of his, and Casey feels herself regressing back to high school.

Snapping out of whatever insane trance she’d fallen under, she jabs him in the chest with her index finger. Using the aggressive action to push him away and give herself some room to breathe. “Just because I don’t know anyone personally, doesn’t mean it doesn’t happen, Derek!”

He snorts, and her finger might as well be made of feathers for all the good it does in getting him to move. “Well, I say since we don’t know anyone who’s ever gotten it, Marti can have some cookie dough.”

Stumbling over her own feet when he leans forward again, she hastily backs up as far into the counter as she can go – ignoring the jabbing pain in her lower back from the sharp edge of the granite and wishing she could wipe the taunting grin off Derek’s face when he immediately notices her clumsiness. “You are not in charge!” 

“Oh, here we go,” Nora mutters.

“Uh, where have _you_ been? I’m always in charge, Klutzilla.”

“Don’t call me that!” She’d thought they left that name behind once they went to university. He _knows_ how much she always hated it, which means he’s using it on purpose to get her riled up. Something that frustrates her almost more than the nickname itself.

Why does he have to be so goddamn difficult all the time?

“Can we not?” Nora interjects halfheartedly, “We were having such a nice night.”

“Then stop being such a klutz.” He ignores Nora’s entreaty, reaching around Casey for the dough, and she angrily knocks his hand away – realizing too late that his attempt with his left hand was a distraction so that he could reach around her with his right and grab one of the already-prepared balls of dough off the tray.

The move, however briefly intended, effectively cages her in against the counter. His body inches from her own – close enough that she can feel his breath against her ear when he leans past her – and Casey panics. His proximity is overwhelming after the week they’ve had, somehow too much and not enough in a convoluted way that Casey has no interest in analyzing right now (or ever), and so she does the first thing she can think of. She shoves his chest – _hard_. Sending him stumbling backwards with enough force that he almost falls. “Don’t touch me!”

Derek recovers quickly – daily hockey drills having blessed him with quick reflexes – and he rights himself before he can be seriously bruised or break something. 

The kitchen grows so quiet you could hear a pin drop. Even Simon stops babbling to Nora in favor of watching her and Derek. And Casey waits for the inevitable string of insults or shouting that’s sure to follow, accusations of attempted murder and threats of swift and merciless retribution, but they don’t come. Instead, they just stare at each other, Derek looking at her in a way she can’t decipher and his face an unreadable mask. Until eventually he exhales sharply and turns back to Marti.

“Here you go, Smarti.” He hands her the dough, and she smiles – although even Marti doesn’t seem oblivious to the sudden tension that’s filled the room. Her blue eyes glancing back and forth between Derek and Casey and her forehead creased.

“Thanks, Smerek.”

Casey stands there awkwardly, folding her arms around herself and chewing on her bottom lip, and another moment of silence passes before Nora cautiously asks, “Are you two finished?”

“Yeah.” She nods, embarrassed, tucking her hair behind her ear and turning around to continue working on the cookies. Accidentally scooping out way too much and creating what will definitely be a monster-sized and no doubt underbaked cookie on the baking sheet. She doesn’t bother to fix it – Edwin will be thrilled when he gets home.

“So… what should we do for dinner tonight?” Nora asks brightly, attempting to bring back the cheerfulness from earlier and propping Simon higher up on her waist. “George and I thought it might be fun for everyone to go out together as a treat. Although,” She frowns, “I suppose we’ll be a smaller group with Edwin and Lizzie gone.”

“Thanks for the offer, Nora,” Derek replies, his voice oddly flat (Casey doesn’t dare turn around – too afraid of what she’ll find), “But I know when I’m not wanted.”

“Derek –“ Nora begins to protest, but he cuts her off with a strange laugh.

“I’ve got plans to catch up with Sam and Ralph tonight, anyway. Don’t wait up!”

Casey watches him leave out of the corner of her eye while putting the cookies in the oven, blinking back tears and fighting the urge to chase after him and apologize. She’d meant to talk to him and straighten everything out as soon as possible, and in the meantime pretend everything was fine so that their family didn’t notice anything amiss, and now she’s failed on both accounts. Failed, and possibly made things a lot worse.

How are they ever going to be able to go back to normal now?

**Notes for the Chapter:**

> So this chapter was supposed to be only like 3k... then it turned into 4, then 5, then 6... and it wasn't supposed to end here, but it was getting out of control. So here's chapter two, and if everything goes as planned I should have chapter three up this weekend. 
> 
> Thanks for reading!


	3. three

**Summary for the Chapter:**

> Oh, baby, I am a wreck when I'm without you  
> I need you here to stay
> 
> \- Line Without a Hook, Ricky Montgomery

**Notes for the Chapter:**

> And then three chapters became four. But on the plus side, I promised this chapter would be posted this weekend and I delivered! So I'll be giving myself a high-five for that one. Hope you all like it! <3

** three. **

Casey wakes up Saturday morning determined to make it a good day and to set everything right with Derek. The autumn sun is bright, the leaves golden, her favorite pink sweater still as comfy as ever, and her jeans make her ass look amazing. Not that that’s particularly relevant, but it never hurts to boost your confidence however you can. She curls her hair into gentle waves, puts on some blue eyeshadow, and applies her favorite cherry lipgloss, then heads downstairs with an extra spring in her step. 

If there’s a weight in the pit of her stomach and a twisting sensation somewhere in the vicinity of her spleen, well, she doesn’t show it. She’s Casey McDonald, for goodness sake! She can handle anything! And she certainly doesn’t balk at the idea of confronting _Derek_ _Venturi_ of all people – no matter how embarrassing the topic may be. If fifteen-year-old Casey can put him in his place, twenty-year-old Casey can certainly do the same.

The house is unusually quiet for a Saturday morning, and when Casey enters the kitchen she finds a note waiting for her on the counter from her mother explaining where everyone is in neat bullet points. George and Nora have taken Simon to a “my toddler and me” parenting class, Lizzie is at soccer practice, and Marti is at her weekly art class. Which means Edwin and Derek must still be asleep upstairs.

Perfect.

She throws on an apron and gets to work assembling ingredients. Step one in her Confront Derek plan is to make him a breakfast that’s so amazing, he won’t be able to help being in a forgiving (and hopefully _talkative)_ mood, and that means going all out. Pancakes, scrambled eggs, bacon, a slew of toppings – including freshly whipped cream and strawberries. Breakfast foods are her specialty, a craft honed from spending the years after her parent’s divorce making Lizzie’s breakfast when her mom had to be at work early, and by the time she’s done he won’t know what hit him.

Thirty minutes later, Casey’s mouth is watering and her stomach is grumbling for much more normal reasons. Everything’s practically ready, and if Derek doesn’t show up soon, she’s going to have to risk his ire by waking him up. Hungry, she steals her own piece of bacon and downs it in three bites while grabbing the orange juice out of the fridge.

Her back is facing the living room, and so she isn’t prepared when Derek, following his nose out of bed, comes into the kitchen and says, “What’s the occasion?”

The awful hacking noise that escapes her throat would be enough to turn her whole face red, if it weren’t for the fact that she’s also choking on the last bite of bacon and trying not to die.

“Casey!” Derek moves fast, his arms wrapping around her from behind – hands making a fist under her sternum and squeezing – and Casey has enough presence of mind to be grateful she’d forced him to take that first aid class when they’d moved in together, thinking it smart to be prepared in case one of them had to save the others’ life. Only, back then she’d been confident _she_ would be saving _him_ from something stupid, not the other way around.

The bacon dislodges from her windpipe and she sags back against him, gasping in relief, her hands clutching at his on her stomach for support.

“Fuck, Case!” Derek practically shouts in her ear, but doesn’t let go. “Were you trying to give me a fucking heart attack!?”

“No.” She coughs again, and his arms tighten momentarily. She can feel his hard body pressed up against her - poised to jump into action – and she pats his arm to reassure him she isn’t about to suffocate again. “No, sorry. That was an accident. You surprised me. I’m fine.”

“You’re never this clumsy when we’re at home,” He grumbles, pulling away and leaning against the counter while running his hand through his messy brown curls, “What’s gotten into you?”

A rush of pleasure runs through her when she realizes he’s referring to their apartment in Kingston as _home_ , but she ignores it in favor of defending herself. “I wasn’t being _clumsy_ , Derek, I was _choking_.”

“Well fucking _don’t_ next time.” He pushes away from the counter and she gapes at his audacity. How dare he be mad at her when she almost died!

Okay, maybe that’s dramatic. She wouldn’t have died – she was still coughing a bit when he jumped into action, and from what she can remember coughing means the body is working to expel whatever is blocking the airflow, but _still._ Is it too much to ask for a _Gee, Case, I’m really glad you’re alright_ and maybe a hug?

“Der- _ek!_ I didn’t do it on purpose! And stop swearing. The kids might hear you.”

He scratches his stomach, the action lifting his white t-shirt and baring a strip of skin above his low-slung pajama pants – still slightly tan from all their trips with friends to the lake over the summer – and Casey has to tear her eyes away when he picks up the note from Nora he’d been scanning and waves it in her face. “This kids aren’t home, and Edwin is snoring like a chainsaw upstairs. Besides, we’re adults, Case, it’s not a big deal. The old rules don’t have to apply just because we’re in George and Nora’s house.”

Casey wants to argue about that, because of course the rules still apply. She lives her life with a strict set of rules, some that are different in Kingston than they are in London, sure, but still. Life without rules would be anarchy! And despite what her therapist keeps telling her about how a little rule-breaking might be good for her every now and then, Casey is still hyper aware of what they are. But before she can muster up a good comeback, Derek rounds the counter and carelessly grabs the plate she’d set out so nicely, not even noticing the placemat she’d put down and cutlery laid out neatly beside it and nearly knocking over the glass, and moves towards the pancakes.

“Stop!” She lays her hand on his forearm before he can pick up the spatula, and Derek lifts his eyes to hers with a raised eyebrow. “You’re not doing it right.”

That clearly wasn’t what he expected her to say, because the rest of the tension leaves his body and he laughs – his eyes twinkling in that way they always do when he finds her particularly amusing. “I’m sorry?”

Feeling self-conscious and trying to hide it, Casey points back at the place setting. “You’re not doing it right. You need to sit down.”

“How am I supposed to get breakfast if I can’t leave my chair? You gonna serve me, princess?” He sticks his tongue in his cheek, smirking at her, and in that moment Casey wishes the bacon _had_ killed her. Because yes, that was her plan, but now he’s gone and made it a _thing_ when it wasn’t before. She was trying to be nice! To apologize! Now she’s about three seconds away from dumping maple syrup in his sleep-tangled hair. 

“Well, I had considered it,” She says sweetly, “But now I think I’ll box everything up and take it up to Edwin.”

“Casey!” He gasps dramatically, his hand over his heart. “You wouldn’t be so cruel to me, would you? And after the way you tried to murder me last night. I mean, that’s what this is, isn’t it? An apology?” He gestures broadly to all the food, and Casey glares at him for seeing through her so easily.

“I’m not sure you deserve one anymore.”

“All this hostility towards the man that saved your life.” He holds out the plate for her to take it, then grabs her by the shoulders and spins her around to start dishing up his breakfast. "Tsk, tsk, Case." 

“Man _handler_ , you mean.” Casey rolls her eyes and shrugs off his hands, picking up the spatula and scooping up four healthy-sized pancakes before moving to the stove to add the eggs and bacon.

“Whatever.” He laughs, taking his assigned seat at the island counter. “Anything that gets me free breakfast.”

She rolls her eyes again, but can’t help the little smile turning up the corner of her mouth. The weight that’s been on her chest since last night has lifted, and although the weight of the conversation that still needs to happen remains, she feels a lot better knowing they’re moving in the right direction. Maybe this won’t be as difficult as she’d thought.

Casey finishes filling up his plate and turns around, catching Derek’s eyes as they rapidly look up from wherever they’d been focused, and he shoots her an easy grin – gesturing for her to set the plate down in front of him.

As expected, Derek dives in with gusto the second the plate hits the counter. Absolutely no time wasted with trivial things like a knife or proper chewing. It should be gross. It _used_ to be gross. But Casey’s used to it now and hardly notices anymore. These days she chooses to take it as a compliment to her cooking, even if she’s tried to make a point of complimenting his cooking _verbally_ in the hope it might rub off on him at some point.

“You gonna eat?” He asks, barely pausing long enough to gulp down some orange juice.

“Yeah.” She nods, chewing on her bottom lip. _It’s now or never, Casey_. “I know you get it with the whole breakfast thing, but I am sorry for pushing you last night.” He freezes, and she quickly amends herself with a joke. “I mean, pushing you so hard. You deserved a small push for calling me Klutzilla.”

She chuckles so he knows she’s teasing, and thankfully he huffs out a laugh, too.

“You call that a push? Case, I play hockey. You’re going to have to try a lot harder than that if you want to take me down.” He winks, and she sighs happily. In this regard, at least, all has been forgiven between them.

_Confront Derek Step One: Check!_

He turns back to his plate, so Casey goes about serving herself breakfast as well. Taking the seat at the counter beside him and pouring herself what’s left of the orange juice, then using her knife to cut her pancakes into meticulously sized pieces. No more choking for her today.

They eat in companionable silence for a few minutes, occasionally bumping elbows and asking each other to pass various toppings back and forth, and it’s nice. If she closes her eyes, she can pretend they’re back in Kingston on a normal Saturday morning and the biggest issue facing them is who will pick the movie for movie night. They’ll get back to that point, though, she’s sure of that now. Just one more quick thing to take care of. Easy-peasy.

( _Ha, yeah right, Casey.)_

“We should talk about it.” The words slip out shakier than she’d intended, and she quickly clears her throat and tries again. “You know, since we’ve got time right now and we’re… alone.”

If she didn’t know him so well, she’d think he had no clue what she was referencing by the way he continues eating until his breakfast it's all gone, but one quick glance tells her his shoulders have gone stiff and the muscle in his jaw is working overtime.

“If you’re fishing for compliments on your pancake-flipping skills, don’t think just because we’re alone that means I’m going to give you any.”

“The way you sucked all that up like a vacuum tells me everything I need to know.” Casey tries to laugh, but it sounds hollow, even to her. “And no, you know that’s not what I’m talking about.”

Derek grabs the bowl of whipped cream and shoves his spoon inside, scooping out a ridiculous amount and shoving it in his mouth. “No idea, Case.” Licking the rest of the cream off the spoon, he makes eye contact with her while deliberately shoving it back into the bowl – and she opens her mouth to yell at him for being disgusting when she catches the calculated look in his eyes. “Something wrong, princess?”

He’s purposely trying to distract her, and she can’t let him get away with it. This is the best chance she’s had to talk to him in days, and she won’t let the conversation get derailed by their usual bickering. “I’m not going to let you turn this into a fight. We need to talk about what happened on Tuesday. The family is starting to notice something’s up.”

“Nothing happened on Tuesday,” He replies stubbornly, “And no they aren’t.”

“Lizzie keeps giving me these looks.” Casey soldiers on despite the mounting unease, determined to see this through. “Marti asked me last night before bed if you and I were fighting again. Even Edwin has picked up on it.”

“That’s hardly an open and shut case, Case.” He laughs at his own joke and stands up, taking his dishes to the sink and dropping them into the basin before turning around to face her again, folding his arms over his chest and leaning back against the counter. The attempt at appearing nonchalant ruined by the way his fingers are twitching and the muscle in his jaw starts clenching again. 

_I’ve got about two minutes before he runs, maybe less._ Casey attempts to diffuse the situation by focusing on continuing to eat her breakfast. Looking at her orange juice, rather than at him.

Derek snorts. “All that means is our sibs have gotten too used to us being away at university these past few years and forgot what it’s like having us home.”

“We come home pretty often, Derek,” Casey points out, counting the flecks of pulp in her cup, “And nobody could forget what we were like in high school.”

“I do leave a lasting impression, don’t I?” He smirks, and she looks at him again, unimpressed.

“The _point_ is – we need to clear the air while they’re gone so that we don’t ruin Thanksgiving dinner on Monday.”

“Hey,” He holds his hands up, “The way I see it, I’m being totally normal. If you’re being stranger than usual, that’s on you.”

His refusal to give an inch when she’s trying to be so nice and polite and patient has her blood threatening to boil, and her temper flares. “So avoiding me for three days in the apartment we share and then refusing to talk to me all weekend is normal?”

Derek shrugs, somehow managing to make the benign action look hostile. “Sure. For us well-adjusted people. I mean, I’ve always known you were needy, Case, but this is a bit much, even for you.”

 _Don’t pick a fight. Don’t pick a fight_.

Casey stands up and moves around the island to face him, curling her hands into fists and gritting her teeth. “Look, I know this is awkward. It’s the first time something like this has happened and we’re both understandably shaken and a little freaked out by it, but you don’t need to be embarrassed about your… your… needs.”

“My needs?” He repeats, and she realizes too late that that was the wrong thing to say, his brown eyes sparkling with unrestrained mischief as he moves from the defensive to pushing his sudden advantage. “And what needs would those be?”

_Crap._

“You know what I mean!”

“I don’t.” Derek grins, waggling his eyebrows. “Enlighten me. Five servings of fruit and veg a day? At least thirty minutes of daily exercise? Lots of water?” 

“Your _physical_ needs. You know.” She waves vaguely in the direction of his crotch, then promptly wants to die when Derek roars with laughter. How did this conversation get derailed so quickly?

“I’m not embarrassed about my physical needs, Case.” His gaze drops to her hips before slowly dragging back up. “Are you?”

It’s an absolutely _filthy_ look, one she’s seen directed at other girls before, but never at her, and heat floods her body from head to toe. She’s well and truly blushing now. She can feel it spreading from the top of her head down across her chest, and she sends a quiet word of thanks to Past Casey for putting on a sweater that hides most of her body’s response. “We’re not talking about me.”

“Maybe we should be. You know,” He leans casually against the counter, “Maybe if you tried touch-”

She shoves his shoulder harder than intended to get him to shut up. (Apparently she really needs to work on her conditioned responses to feeling cornered by Derek.) “This isn’t about me! This is about you and the extracurricular activity I witnessed!”

Unperturbed, and still remarkably self-assured given the conversation, Derek continues to smirk at her. “Jacking off is _not_ an extracurricular activity, but of course you’d see it that way. Is everything school-related in that keener brain of yours?”

“No.” Her blush deepens against her will. Derek can smell her weak spots like a shark smells blood, and she knows she’s not helping herself gain back any ground here, but she can’t help thinking of the fake words she’d heard him say in her head about working for her orgasms and how his comment hits a little too close to that.

“I bet it is.” He chuckles darkly, tongue darting out to wet his lips. “Do you grade your orgasms, too? Points added for good foreplay, points deducted for –“

She slaps her hand over his mouth with a screech. “Der- _ek!_ ”

Well, there goes their clean record of never discussing orgasms. This conversation _really_ isn’t going how she planned.

Refusing to relent, Derek licks her palm, and she pulls it away to wipe off on her pants with disgust. “You know,” He steps forward, “We wouldn’t be here right now if you hadn’t invaded my privacy. Were you looking for blackmail, or was it just general curiosity? Because if it was blackmail, you know how motivated I can be when getting revenge.”

Something about the way he says it doesn’t make her fear retaliation, instead sending warm sparks through her veins, and she folds her arms over her chest to try and contain the sudden confusing burst of desire she feels in her gut.

This is _Derek_. These feelings are wrong!

(But then why do they feel so right?)

“Obviously I wasn’t trying to see that, don’t be gross! I’m sorry I walked in on you – okay? I should have knocked, but when I heard you say my name I thought –“

“I didn’t say your name.” Gone in an instant is his rogueish smile. The easy flirting that had been there only a second ago twisted by the venom in his voice.

It’s like stepping outside expecting sunshine and getting smacked in the face by a pelting hailstorm. Entirely discombobulating and painful. And Casey can’t make heads nor tails of his sudden Jekyll and Hyde transformation. “Yes, you did. Why do you think I came running?”

“Because you have a nasty habit of bursting into my room, unwanted.” He backs away, and this time it’s Casey that tries to close the distance – frowning at the pinched look on his face.

“That’s not fair. I’ve been very respectful since we moved in together.”

“And yet – you weren’t this week, were you?” He glares at her, challenging, and Casey throws up her hands in exasperation.

“Which I’ve apologized for, and I’ll apologize again. I’m sorry. But Derek – the woman –“

“What?” He snarls, daring her to finish her sentence, but there’s something hiding behind his anger. Something nervous and almost… afraid. But what would Derek have to be so afraid of?

“She looked like me,” Casey finishes with a whisper, feeling on the precipice of something huge. Momentous and life-changing, if they’re ready for it. If she’s willing to admit to herself something she’s known since she was sixteen.

He laughs in her face.

“Ha! For someone who accuses me of having a big ego, you should really look in a mirror. How did you even have time to look at her face? I didn’t notice it at all.” 

That feeling in her chest isn’t disappointment. It _isn’t._ “Don’t be _mean_.”

“I’m not being mean.” He snaps, then, as if noticing her expression and realizing how harsh he sounds, somewhat softens his voice before continuing. “It just wasn’t about you, Spacey. Why would I care what the girl looked like, as long as she has nice tits and the right parts?”

“Do you have to be so crude?” Oh god. She’s going to cry. _Get it together, Casey McDonald. Of course he wasn’t getting himself off to thoughts of you. This is what you wanted to happen here. This is_ good. _He’s your stepbrother – you’re not_ supposed _to have feelings like that for each other._

But if this is such a good thing, why does it hurt so much?

Derek backs away again, and she knows their two minutes are up. “We’re talking about porn. Am I supposed to try to act all posh and polite? It is what it is. I’m sorry you had to see that – I’ll make sure my door is locked next time – but there’s nothing else here to discuss.”

He spins around and marches out of the kitchen, and she lets him go.

****

Red and blue lights pulse throughout the packed club, bouncing off the disco balls strung from the ceiling and the chrome surface of the bar. The crowd on the dancefloor swells with each beat, and the scents of sweat and beer and cocktails mix together until one is hardly discernable from the other. It’s the exact opposite of the kind of place Casey normally hangs out in on a Saturday night (or ever), but when Emily had called and invited her out to catch up, she’d jumped at the opportunity to get out of the house.

Derek had gone out again with Sam and Ralph, and she’s determined not to think about him anymore than she has to for the foreseeable future. It’s too… painful? Hard? Confusing? Ugh. Whatever it is, it’s too much.

“So Lizzie’s got a girlfriend, huh?” Emily slides Casey’s strawberry daiquiri across the table when she sits down, lifting her margarita to her lips. “That’s exciting!”

“Well, I don’t think they’re official or anything yet.” Casey smiles and takes a drink, savoring the cool, sweet flavor. “But during the movie last night Katie held her hand, and she asked Lizzie out to dinner next week, so it’s looking like it’s moving in that direction.”

Lizzie’s excitement had been explosive when she’d returned from her date the night before (it had been officially defined as a date after the whole hand-holding development), and proceeded to keep Casey up until one in the morning going over every single second of the night in detail. It was lovely to see her little sister so excited, and it did wonders for Casey’s overall mood (which is probably why she’d been so stupidly optimistic that morning during breakfast – but no, she’s not thinking about that tonight). At least one of them is finding success in that part of their life.

Emily smiles, knocking her glass against Casey’s. “I’m happy for her. Lizzie’s awesome, and she deserves an awesome life.”

“Thanks!” Casey grins. “I’ll tell her you said that. How have things been going with Sheldon?”

Emily launches into a long speech about how great things are with her and her boyfriend. What a welcome surprise it was when he announced he was coming back to London to attend Western for his final two years of university, how she’d known the second she saw him again that she needed to break up with the guy she was seeing – just for a _chance_ with her high school sweetheart who she’d never really gotten over. How sometimes you just _know._ All while a waitress keeps bringing them replacement drinks at a steady rate.

“We’re looking for an apartment together,” Emily announces with a wide smile, finishing off her third margarita with a slurp.

“Already?” Casey’s eyes go wide, her eyebrows shooting towards her hairline. “You’ve only been dating again for a month and a half. Isn’t that… fast?” Her longest relationship so far at Queen's had lasted sixth months, and at no point during that time had she felt anywhere close to ready to take such a big step. 

Emily laughs and waves her hand dismissively. “We’ve known each other practically our whole lives. Besides, he already spends most of his nights at my place and my flatmates are starting to complain. It just makes sense. Plus, Sheldon really wants room for a piano, and his current apartment barely has room for a couch and TV - not to mention the three other guys living there.”

“Weird to think of any of us being old enough to move in with a partner.” Casey tips her glass back to get the rest of the frozen slush at the bottom. It’s her fourth and she’s starting to feel the rum kicking in, but she waves towards the bar for another one anyway. She feels good. Free. _Floaty._ Maybe rather than trying to deal with Derek like an adult, she’ll just take up drinking frozen cocktails from now on.

“You moved in with Derek.”

The glass slips from her fingers and she barely manages to catch it before it can hit the table and shatter. “That is… _totally_ different. Like – different languages, different. Different _universes_.” She holds her hands out wide to each side, as far apart from each other as she can go, and almost knocks the drink tray right out of the waitress’s hands.

“Casey!” Emily half-shouts, half-giggles. “Careful!”

Casey grimaces at the frowning waitress as she sets down her new daiquiri. “Sorry.”

“It’s not that different, really,” Emily continues once the waitress is gone, “I imagine the only difference would be the sex.”

 _That_ about sends Casey to the floor, and she drops her head in her hands and groans. How much alcohol will it take for her to blackout? Because that’s seeming like the only viable escape from her life at this point.

“As in you _aren’t_ having it!” Emily quickly clarifies, seeing and misinterpreting Casey’s distress. “And Sheldon and I are.”

“Obviously.” Casey mutters, rubbing her temples.

“Obviously.” Her friend agrees. “Because that would be, you know,” She gestures vaguely, “Weird.”

Wearing a sweater to a busy club was the wrong idea. At the time she hadn’t thought much of it, given the temperature outside. Wearing a sweater meant she wouldn’t need to worry about carrying a jacket or coat. But now she’s seriously overheating. “Can we not talk about Derek in this context?”

“Right! Right, sorry. Sorry.” Emily winces sympathetically and reaches across the table to pat Casey’s arm. “I forget you guys are related sometimes. You’re just so… you. I’m not sure there’s a category for what you and Derek are.”

“We’re not,” Casey disagrees, out of necessity more than habit this time. She literally cannot think of Derek as related to her in any way. Not tonight.

“What?”

“We’re not related. We’re just… sharing family names on a legal document.”

Emily gives her a funny look, but chooses not to argue and for that Casey is grateful. “Whatever you say, Case. Like I said – unique category.”

Desperate to change the topic, Casey shakes her thoughts clear and lifts her head again, reaching for her new daiquiri and the giant basket of Cajun fries the waitress had brought over for them to share. “Let’s get back to you and Sheldon. Have you toured any apartments yet?”

Emily takes the chance and runs with it, bringing up the apartment listings on her phone and showing Casey all the places they’ve toured so far and talking about the pros and cons for each one, and Casey lets herself get lost in the conversation, drinks, and, eventually, dancing, until hours have passed and she’s stumbling out of a cab and walking up to her front door.

She’s past tipsy, but not so drunk that she doesn’t realize it’s well after midnight, and Casey takes care to close the front door gently behind her before tiptoeing upstairs, not bothering to turn on any lights. She knows this house like the back of her hand, and there’s a light coming from one of the bedrooms that’s enough to get her to the bathroom.

Her nighttime routine is a bit more difficult to manage with her hands not following her instructions as precisely as she’d like, but eventually she manages to wash her face and brush her teeth and get the tangles out of her hair. What she’d really like is to take a shower, but as she shares Lizzie’s room whenever she visits home, that would run the risk of waking her up, and Casey doesn’t want to disturb her sleep.

Making her way out of the bathroom, she turns to go to bed, but stops with her hand on the doorknob. The light she’s been relying on to keep from running into anything is coming from the yellow room that used to be Lizzie’s before she moved out – the one that had been turned into a small guest room with a double bed that Derek always claims. (He’d resented having to give up the room that had been his since birth, but it had been inevitable when Simon was born, and it was hard to argue that he needed the space more than his new baby brother. Especially when he’ll probably never live full-time in this house again.)

Almost of their own accord, Casey’s feet start moving down the hall towards the light, and she peeks through the crack to see Derek propped up in bed, the reading glasses only she knows about on his face (she ~~loves~~ hates that they actually make him _hotter)_ , and his focus fixed on the book open in his hand.

“I hope you’re not getting ahead of me.” She pushes the door open a bit and leans her hip against the frame, smiling so that he knows she comes in peace.

They share more secrets than just his reading glasses. At the end of the previous school year, when she’d been having a bigger freak out than usual and was in real danger of it turning into a full-blown panic attack, Derek in a moment of desperation had suggested he read to her from the book on her nightstand. The offer had taken her so by surprise it had stopped the panic attack in its tracks, and she’d wordlessly nodded – surprised all over again when he actually did it.

Since then it’s been a _thing._ Not something they do often, but every once in a while when one of them needs to relax more than usual – her before a test or big paper, him before a game – they’ll curl up on opposite ends of their couch and hand the book back and forth until one of them falls asleep.

She’s not sure why, exactly, it’s such a secret. Even they don’t talk about it outside those nights. She could blame it on the age-old argument that she and Derek can’t stand each other and don’t want anyone to get the wrong idea that they’re _bonding_ or something, but that isn’t it. It’s been a long time since they felt any real antagonism towards each other, this week aside, and it’s just… it’s special. She doesn’t want the outside world with all its opinions stepping in and ruining it.

Derek looks up, less surprised to see her than she expected, but perhaps he put two and two together when he heard someone come up the stairs this late at night. (She certainly doesn’t think he stayed up waiting for her to come home safe or anything. That would be ridiculous.) “I’m not.” He holds the book higher so she can see the hockey player on the cover. “It’s about Ken Dryden. Coach recommended it to me. Said he thought it might be good for me to learn more about the psychology of a professional hockey player, or something.”

“I think that’s great!” Casey exclaims, and Derek points towards Marti’s room next door, the meaning obvious. “Oh,” She winces, dropping her voice to a whisper, “Right. Sorry.”

She should turn around and go to bed. It’s late, he’s busy, she’s tired. This is a very bad idea. Instead, she steps further into his room and shuts the door behind her, blaming momentary alcohol-induced insanity when she kicks off her shoes and crosses the carpet to lay down next to him. “Read it to me.”

Derek doesn’t say anything, and after a long stretch waiting for him Casey pries her eyes open to find him watching her with an inscrutable expression.

“Are you drunk?” He finally asks, poking her in the shoulder with his index finger. “You smell like a club. How much did you have?”

“Only a few strawberry daiquiris.” She shrugs, proud of the way the words don’t slur at all, and wriggles around on the bed until her head lands on the pillow and she’s in a more comfortable position. All she wants right now, besides an empanada (she’s not sure why, but sweet cocktails always make her crave South American food), is for Derek to read to her so that she can fall asleep. She’d never tell him this, but he has a nice reading voice.

“Thanks.” Derek laughs, and Casey blushes when she realizes she said that out loud. _Damn it._

“Get on with it then.” She pokes him in the ribs to retaliate, and he huffs out a laugh and bats her hand away, and Casey smirks at having found his ticklish spot on the first try. See? She’s totally not drunk. A-plus coordination for her so far.

“You really want me to read to you about hockey?”

“I think I’ve attended enough of your games at this point I won’t get too confused by the terminology,” She jokes, nodding and closing her eyes again, “Just keep reading wherever you left off.”

She knows him well enough to know that he wants to say something else, but whatever it is he must decide against it, because after another moment of silence he quietly clears his throat and begins to read, and Casey settles in with another soft smile on her face.

Just a few minutes of this, which she can easily dismiss as a side effect of being pleasantly tipsy and not thinking straight, and then she’ll get up and go get in _her_ bed where she belongs. That’s all she needs – just a few more minutes.

**Notes for the Chapter:**

> The reading to each other bit is a nod to one of the greatest ships of all time, Pacey and Joey. The OG enemies to friends to lovers.


	4. four

**Summary for the Chapter:**

> Give me your lips for just a moment  
> And my imagination will make that moment live  
> Give me what you alone can give  
> A kiss to build a dream on

**Notes for the Chapter:**

> I had some computer trouble this week, but the final chapter is here! And about twice as long as I intended it to be (what else is new?). I hope you all enjoy the conclusion to this story. 
> 
> CW: The second half is very explicit.

** four.  **

Everything’s fuzzy when she wakes up. Her brain feels like those jars of cotton balls on the shelf at the doctor’s office, fluffy and crowded and pressed up against the glass on all sides. As far as hangovers go, it isn’t the worst one she’s ever had, but it isn’t exactly pleasant, either. And along with the headache it seems to include some unfamiliar side effects like making her pillow smell different and a heavy weight around her waist – two signs that she’s probably going to be sick. She can’t be sure, though. Her body’s in that weird in-between stage where she might be fine after a few minutes of breathing through her nose, or she might vomit.

Rubbing the gunk out of her eyes, the first thing she notices is the glass of water on the nightstand next to two aspirin pills, and Casey reaches out for both – making a mental note to thank Lizzie for being so thoughtful. Later. When she’s feeling more human. The water helps the dry, cotton feeling in her mouth fade, and she drinks almost half of it before putting it back and laying her head back down.

From what she can tell by the grey light filtering in through the open blinds, it’s some time early to mid-morning, and she’ll need to get up soon if she’s going to have any hope of taking a warm shower. Derek likes his practically scalding, and if she waits too long he’ll get there first and all the hot water will be gone. It’s a system they’ve perfected back in Kingston – her being a natural early riser and Derek… _not_ – and far be it from hungover Casey to mess with a good thing.

Her body, however, seems to have different plans, and Casey feels herself sinking back into the warm pull of the blankets and the soft mattress, her eyelids fluttering shut – reasoning that since it’s Sunday and they’re on vacation Derek will probably sleep until noon. That is, until something finally clicks in her brain, and she pries her eyes open to look at the wall across from the bed. The _yellow_ wall.

This isn’t ~~her~~ Lizzie’s room.

She’s in the guest room. The room normally occupied by Derek. Which means that dream she had about drunkenly climbing into bed with him and demanding he read to her (about _hockey,_ of all things) wasn’t a dream at all, but very much real. And that also means that the weight around her waist isn’t lingering nausea from too many daiquiris, but a very real, very solid human arm.

_Derek’s_ arm. 

It is a testament to her growth (and the benefits of seeing a therapist for the past two years) that she doesn’t instantly freak out. Old Casey would definitely have screamed, probably elbowed Derek in the ribs, hurled insults, and ran from the room promising to burn every article of clothing that touched his sheets. But New Casey squeezes her eyelids shut, counts to twenty and then back down again, and focuses on regulating her breathing. In through the nose for four seconds, hold it for seven, and then out through the mouth for eight, repeating the cycle four times.

_This is fine,_ she thinks slowly, trying not to notice the faint intervals of Derek’s breath on the back of her neck. They’ve fallen asleep on the couch before, so this really shouldn’t be a big deal. Sure, they’ve always been on opposite ends of said couch, and sure, this is very much a _bed_ and that’s new territory for them in a way both terrifying and thrilling, but still – not entirely out of the ordinary. Nothing to freak out about and no reason to overreact. Accidents happen.

Feeling much better, Casey starts to get out of bed when the second realization of the morning hits her. If she’s in Derek’s room, that means it was _Derek_ who got up and got her a glass of water and some medicine. She’d never believe it; except she can see his book on the nightstand and his glasses are there folded neatly next to the water like it was the last thing he did before falling asleep and if anyone else had caught her sleeping with him they wouldn’t have left them alone until morning.

This means that Derek knew she was asleep in his bed and rather than wake her up and kick her out, he set aside things he knew she’d want whenever she awoke and then climbed back into bed with her. And, whether or not the night started out that way, now he’s _snuggling_ her. The man who doesn’t do hugs is spooned up behind her like there’s no place he’d rather be.

As if to prove her point, Derek shifts - his knees bumping up against the back of hers while his nose buries itself further in her hair - and lets out a breathy sigh.

_If he wanted me gone,_ Casey rationalizes, heart thundering in her ears, _he would have kicked me out last night. Ergo, at least some part of him must want me here._ That’s enough to stop her from running, at least for now.

Slowly, careful not to disturb him (and oh, how times have changed if she’s actively trying _not_ to brutally wake him up), Casey turns over so that she can look at his face – taking advantage of one of the rare moments in which she can simply observe him without risking being caught.

He looks so peaceful like this, cheek pink and creased from being pressed against the pillow, his mouth slightly open, hair messy and falling over his forehead. He’s been letting it grow out lately, long ago abandoning his efforts to tame his natural curls, and Casey secretly _loves_ it (he’d shaved his head on a drunken dare last year – something he’d instantly regretted upon sobering up – and she likes to think her absolutely horrified reaction had helped lead to this current result). Triple checking his face to make sure he’s fully asleep, she raises her hand to find out for herself if it’s as soft as it looks. 

She barely touches it at first, stroking one errant curl with the tip of her finger, but when he doesn’t wake up she holds her breath and allows herself more liberties. It’s just curiosity, that’s all this is, nothing… weird. And when she runs her hand through the mess, brushing it back from his forehead, she’s inordinately pleased to discover it’s even softer than she’d expected.

It’s nice, being here with him like this. Relaxed and easy. Probably because he isn’t awake to harass her for being so affectionate or tease her over something she’s said. Although, if she’s being honest, she doesn’t mind the teasing so much. Not when she’s the center of his attention and he’s smiling at her that way he does. Even if it makes her blush, like the way he called her out yesterday for her _needs_. If only he knew.

_I need you,_ she thinks, whispering even though the words are locked safely inside her head. She doesn’t dare confess out loud, even if he is dead to the world, but it’s a relief to finally admit it to herself. No mincing words, no caveats, just the simple truth she’s been hiding deep inside her heart since her sixteenth birthday. There had been attraction before that day, of course. She didn’t recognize it for what it was until much later, but all that open hostility could only come from two hormonal teenagers harboring feelings for each other while being trapped together in a situation they couldn’t avoid or change. It was bound to be explosive. But when she’d woken up at the hospital to find Derek waiting for her with a birthday video from all her friends and family, something had taken root deep inside, and, despite her best efforts, that feeling has only grown since then.

She trails her fingers down around his ear and caresses his jaw, before returning to his hair – her fingernails accidentally scraping across his scalp, and Derek lets out a sleepy moan from deep in his throat. In hindsight that should have been her first warning, but Casey doesn’t register the sound quickly enough to remove her hand before his brown eyes are fixed on her face.

Caught red-handed, Casey freezes like a deer in the headlights. How is she going to explain this? Lying in his bed, nose inches from his own, hand combing through his hair like it belongs there. Like this is something they do frequently and not completely new territory. Is this the part where he kicks her out? Mocks her for being weird and creepy or berates her for invading his personal space yet again?

“Trying to fix me in my sleep, huh?” Derek interrupts her panic spiral, his voice thick and the corner of his mouth crooking up. “And here I thought you said _I_ was the manhandler.” His eyes close again and he tilts his head as if to encourage her actions, and Casey hesitantly releases the breath she’d been holding.

“Your hair is a disaster in the morning.” She tries to sound light and teasing, but it comes out closer to raspy and breathless, and she struggles to remember why all of this is a Terrible, Horrible, No Good, Very Bad idea.

“Hey,” He lifts his shoulder in a half-hearted shrug, playing innocent, and in the process tightens his hold around her waist, “You get what you get. You’re the one who wanted to sleep with me.”

He’s genuinely smirking now, radiating mischief even with his eyes closed, and Casey gasps and mumbles, “Der- _ek_!” Afraid that even a hint of impropriety will have their whole family knocking down the door in a heartbeat. She pulls her hand back from his hair, surprised that she’d let it linger so long, and clutches both arms in front of her chest like a shield. Although whether she’s shielding herself from his actions or her own, she isn’t sure. She’s not entirely convinced that this isn’t about to lead to one of his pranks.

“Can’t say that I blame you.” Derek opens his eyes again just so that he can wink at her, and Casey protests by poking him in the chest.

“That’s not what this is.”

His eyes lock onto hers across the pillow and something in his expression makes it impossible to look away. It’s like he can see through her – right past the banter and down into her heart and soul. “Then what is it?”

Casey opens her mouth, but finds no reply. How can she wave her hand and condense everything she feels into some glib answer? It would be easier if she knew what Derek was thinking, but she’s never been able to figure him out. Not completely. She’s got an entire journal full of notes dedicated to the mystery that is Derek Venturi’s mind, and yet for all her research, she hasn’t been able to decipher the way he looks at her sometimes.

At a loss, she drops her gaze to stare at his mouth instead, wishing it were possible to magically draw the words she wants to hear from his lips.

“Seriously, Casey.” Derek lifts his hand from her waist to cup her chin and force her to look at him again.

“I- I don’t know,” She stammers, a blush rising to her cheeks, “A mistake.” It comes out more of a question than a statement, and she’s not sure if she means the mistake was getting into bed with him, sleeping next to him all night, or staying in bed this morning after she woke up. Maybe all three. Or maybe she just knows that all of this will be easier to handle if they both write it off as a drunken accident.

But Derek doesn’t take the easy out like she’d expected. Instead, he hums noncommittally, moving his hand from her chin to her neck and brushing her hair back over her shoulder. “Not a good enough answer. Try again.”

This isn’t them. They don’t do this. Touch each other like this. They aren’t… intimate. They wrestle and they push and shove and tickle and… and… and Derek is stroking that spot underneath her ear, the one that turns her body into jello, and Casey shifts her hips forward. “Maybe I just –“ She hesitates, licking her lips, “Maybe I just wanted to feel close to you.” Then, freaking out a little bit at her own honesty, she hastily amends, “You know, because we’ve been fighting. I wanted things to be okay between us - I didn’t mean to fall asleep here.”

“So last night was just a drunken attempt at a friendly truce, nothing more?” Derek arches his eyebrow, calculating, and Casey scrambles for the most socially acceptable answer while trying not to notice the fact that his hand is still very much touching her.

“Right. Yes. Obviously.”

“You’re a terrible liar.” He snorts, lightly tugging on her hair. Casey opens her mouth to retort (just because someone believes lying is _wrong_ doesn’t inherently make them bad at it!), but he beats her to it. “I lied, too, you know.” He speaks so quietly she almost doesn’t hear him, and she scrunches her forehead and cocks her head – inadvertently granting him more access to her neck. Access he takes advantage of by tracing his fingers down to her collarbone and back, leaving a trail of fire in their wake.

Her brain takes a second to catch up, but when it does she’s even more confused. “Lied about what?”

“When I said it wasn’t about you.” He glances down between their bodies, cheeks pink, and the lightbulb goes off over her head just in time for her blush to deepen into a nice scarlet. “It didn’t start out that way,” He rushes to explain, “I mean, look, I’m not ashamed to admit that I watch porn every once in a while, but I swear I’ve always tried to find videos with women who _don’t_ look like you. I knew if I did, I’d spend the entire time trying to jack off while hearing your voice in my head going off about feminism and boundaries and respect.” Casey giggles nervously, strangely flattered, and Derek shoots her a quick smile. “But a couple months ago I stumbled upon this porn star, the one you saw, who looked so much like you it was kind of scary. I almost asked if you’d taken up a part-time gig and not told me.”

Casey swats his chest and scoots closer. “Derek! I can’t believe you thought I’d do porn.”

“I couldn’t believe you’d do porn and not spring for a nicer apartment!”

Casey laughs again and this time Derek joins in, and the knot that had lodged itself in her chest over the weekend starts to loosen. “So you’ve been watching her for a couple months? I’m surprised I didn’t catch you sooner.”

“No,” He shakes his head, his hair falling on his forehead again, and Casey resists the urge to brush it back, “I couldn’t. It felt even _more_ violating. It was torture, too, believe me – like I’d found, like, the nirvana of all porn, but wasn’t allowed to watch it. And knowing it exists was just more of a reminder that I couldn’t have the real thing.” His words stutter for a moment in that way they only do when he’s forcing himself to talk about something real, and her breath hitches at this near confession, but Derek continues on before she can do something crazy like kiss him. “It put me off porn entirely. Which was the worst timing to go cold turkey, because then that lame-ass dickwad Aaron or whatever dumped you and you got all needy and wanted to spend all this _time_ together watching movies and eating ice cream and back massages and, Jesus, _fucking_ hell Casey, I’m only human.”

He drags his hand down her arm, burning her through her sweater, and Casey shifts her head and bumps her nose against his. “So you gave in?”

He glances at her lips, shifting his head back to a semi-safe distance before nodding. “You were wearing that sports bra and legging combo before your dance class that makes your body look, like, crazy hot and doing those warm-up stretches in our living room and I couldn’t take it anymore.” 

She does like that pale blue combo the best out of all her athleticwear, but she had no idea he was taking notice. Now, well… now it’s going to have to make more frequent appearances in her rotation if it gets these kinds of results. Derek was turned on by her. Turned on to the point that he had to masturbate to relieve the pressure. That knowledge makes her feel… powerful. Desired _. Needed._

“Are you mad?” He rubs her arm again, back up to her shoulder and then down over her ribs – bringing his hand back to rest on her waist, only this time her sweater has ridden up a bit and there’s a sliver of skin available that wasn’t there before, and it’s something that does not go unnoticed because his pinky promptly starts stroking back and forth and sending shivers down her spine.

Speechless, she simply shakes her head, and then it’s Derek’s turn to bump her nose with his – his lips mere centimeters from hers now. He hasn’t said the words exactly, but all of this _must_ mean he feels the same way she does.

Taking her response as a sign of encouragement, Derek slips his whole hand underneath her sweater and slides it around to rest on her lower back, and Casey inches her hips forward again until there’s almost no space left between their bodies.

She needs to touch him. Needs to feel that he’s real, that this is happening outside her wildest dreams, needs something solid to tether herself to before she floats away. And so she reaches out and touches his chest, gliding her fingertips across his collarbones and down over his pecs, wishing his thin, threadbare t-shirt wasn’t in the way so that she could really feel him. Finally touch the lean muscles and tanned skin she knows are hiding underneath.

“Casey,” He whispers, and she looks up to find his pupils blown wide and his lips shiny where his tongue had darted out to wet them.

_Take a risk, Casey,_ her therapist’s voice says in her head, _it’s okay to break the rules sometimes._

Maybe she was just waiting for the right rules to break.

“You are wanted, Derek,” She replies, remembering his self-deprecating joke to Nora on Friday and hoping he doesn’t really feel that way, “I want you.”

His grin is blinding, but she barely has time to appreciate it before he’s closing the gap between them, his lips starting to lightly brush against hers when the doorknob rattles violently.

“Smerek!”

They freeze, mouths grazing each other in an entirely unsatisfactory not-quite-kiss, and Derek’s irritated groan is almost comical when he lifts his head to glare at the door. “What do you want, Smarti?”

“It’s late! You promised you’d take me to the park this morning so we could fly kites. The wind is perfect!”

The doorknob shakes violently again, and Casey twists her head to doublecheck that the notoriously fickle lock is still holding. Derek must have done that before bed, and the implication sends a burst of heat from her head to her toes. “You’d better go before she comes back with an axe. I need to take a shower, anyway.”

“I could join you,” Derek offers with a wicked smile, and Casey tugs the pillow out from under her head to hit him with it. “Hey!”

“We are not doing that in this house,” Casey hisses, even though part of her finds the idea exciting. Sneaking around, stealing kisses, surreptitious glances, and footsie underneath the dinner table. Satisfying some of the dreams she’d had back in high school that she never dared acknowledge – even in her dream journal. Just thinking about it has her rubbing her thighs together. Which is a mistake, because Derek is still very much pressed up against her, and he practically leers when he feels her fidgeting.

“Are you _sure_?”

Casey’s saved from having to answer by Marti shouting through the door again. “What are you doing in there!?”

Derek mutters something that sounds an awful lot like _not the thing I_ want _to be doing_ and pushes himself up and over her, barely managing not to tumble off the bed before righting himself and marching over to the door. Only opening it enough to stick his head through the gap.

“I’m getting dressed, and if you promise to be very nice and wait downstairs, I will be ready to go in five minutes.”

“Fine. Mom also said to ask if you’d heard from Casey. Nobody’s seen her this morning.”

“Nope!” Derek responds, over-emphasizing the P and already closing the door. “See you in five, Marti.”

Casey sits up with a jolt. Marti meant Nora and that sends ice water rushing through her veins. Nora, her mother, who Marti calls Mom now, because she _is_ Marti’s mom in every way but by blood. Because she and Derek share a family and for a few blissful moments Casey had forgotten that. What are they going to do? How would they even begin to explain? What can they possibly be think-

Derek tugs his shirt over his head and throws it at her face, and Casey splutters in surprise as she pulls it away and drops it on the floor.

“What are you doing?” She tries to glare at him, she does, but then her brain catches up to her eyes and realizes she’s staring at shirtless Derek, only this time she’s presumably allowed to look. And look she does – taking in everything from the smattering of hair across his chest down to the faintly defined muscles of his abdomen to the happy trail disappearing into his pajama pants.

“Getting dressed.” Derek loops his thumbs in his waistband, his intentions clear, and Casey slaps her hand over her eyes.

“I’m still in the room!” As if he needs the reminder. As if she doesn’t know he’s doing this specifically to get a rise out of her. She can hear him grinning at her from her spot glued to the bed.

“You looked far away,” He explains, easy as anything, “I thought I’d remind you it’s worth it to stay focused on the present. You know – eyes on the prize.”

She can hear his pajamas pants fall to the floor with a whoosh, and she decides to bring her other hand up to cover her face – just in case one wasn’t enough. “I’m not sure I want to know what the prize is in this context, and I don’t want to see you naked.”

“It’s almost embarrassing, Case, how bad at lying you are.” Derek snickers. “I might believe you, if you hadn’t been groping me when you thought I was asleep.”

“I was _not_ groping you,” Casey shoots back, turning up her nose, “If anything, it was an affectionate caress.” She hadn’t even touched him below his chest, for goodness sake. Her actions were entirely innocent.

(Her thoughts, however…)

He laughs at her, but it’s warm, not mocking, and Casey can’t help but smile in spite of herself. _This is no good_. _I’m going to have absolutely no defenses against him now._ He’s going to try to flirt his way out of everything, and at least half the time she’ll probably let him.

“Either way, we’re doing this, right?” He insists, and she knows what he’s really asking. _We’re together now, right?_

She drops her hands, half-grateful, half-disappointed to see him already zipping up his jeans, and nods. “Yes.”

Derek gives her a lopsided grin, obviously pleased by her answer and preening under her appreciative gaze. “Then what’s the problem?”

Casey takes a moment to think up an answer that might turn this back around on him, thoughtfully tapping her chin. “I suppose I have already seen everything you have to offer.” She gestures vaguely with a sigh, feigning disappointment, but Derek’s response is unfazed.

“Baby, that’s just the tip of the iceberg, believe me.” She pulls a face, and he laughs. “That a no on ‘baby’?”

“Definitely.” Terms of endearment that infantilize one’s partner have never been her favorite, and that isn’t about to change just because she gets a little thrill at the novelty of such terms being directed at her by Derek.

_I’m dating Derek Venturi_. The thought takes her breath away.

“Noted.” He pulls a clean t-shirt out of his duffle bag, never bothering to unpack when they visit London, despite the empty chest of drawers against the wall, and gives it a quick sniff before pulling it over his head. “We’ll have to work on pet names later.”

“Why not just ‘Casey’?” It sounded so nice when he’d said her name earlier, all sleepy and intense, and she would not mind hearing that again. Every day, in fact.

“That’s a keener’s name,” Derek quips, and Casey glares at him.

“Der- _ek_!”

“That’s it –“ He points at her before giving her two thumbs up. “That’s the one for me. Why would I want something all gross and romantic and coupley when I can have that?”

“I’m becoming increasingly fond of ‘jerk’,” She deadpans, folding her arms over her chest and rolling her eyes. 

Derek smirks, sticking his tongue in his cheek. “I think you mean _jerk off_.”

“Okay, get out.”

“It’s _my_ room!” He protests.

“I don’t care.” She shakes her head, waving him out the door. “Time to go.”

“Fine, fine!” He throws his hands up in surrender and turns to grab the door handle, and Casey starts to relax – ready to take some time to herself to come to terms with this insane turn of events – but then he spins around without warning and crosses the room, grabbing her wrist and hauling her to her feet and planting a kiss firmly on her lips.

His mouth is warm and insistent, one hand clutching her hip while the other comes to rest underneath her jaw, and Casey’s left uselessly clutching at his shoulders – fully succumbing to the fireworks going off inside her brain when she feels his tongue just barely graze hers. Teasing. _Promising._ Kissing her with an intoxicating mix of confidence and tenderness that has her head swimming and her knees going weak.

After what feels like forever, and yet not nearly long enough, they finally pull apart to catch their breaths, and Casey can’t help but giggle and press her forehead against his. She is in so much trouble. And yet, she can’t bring herself to care about anything but the happiness she feels right now in this current moment.

“Yeah,” Derek huffs out a laugh, “We’re _totally_ doing this.”

****

It turns out that having a heart-to-heart with your stepbrother, and then _kissing_ said stepbrother, in the house your parents share is not exactly the best way to start off a new relationship. Particularly when said house is also full to bursting with your entirely too inquisitive siblings. Apparently Lizzie and Edwin haven’t entirely given up on their amateur detective careers, because every time Casey and Derek touched one of them seemed to be around to give them a curious stare, and even Marti pointed out that they were in a better mood than they had been when they’d arrived and wanted to know if that meant they’d “kissed and made up” (a new term she’d learned and one that made both Derek and Casey spit out their drinks in unison).

The one time they’d snuck into the garage to make out, they’d nearly been caught by a clueless George taking out the garbage. He’d waved as he waltzed past them, not questioning why the two of them were tucked away behind one of the storage shelves looking guilty as sin, and Casey’s never seen Derek as pale as he’d been in that moment – awkwardly waving back to his dad and subtly adjusting his jeans.

As such, Casey’s fantasy of sneaking around had fizzled out under the very real threat of being discovered. If they are going to make this relationship work, then they’ll have to tell their family someday, but she’d prefer if they could at least wait until they’ve been together for more than forty-eight hours before dropping that bomb on everyone.

Which is how they ended up here, on the road to Kingston, bellies full of good food, a stack of Tupperware in the back seat stuffed with leftovers, and enough sexual tension between them to power the Titanic.

Shifting in her seat, Casey watches the mix of sunlight and shadows as they pass over her and Derek’s hands where they’re loosely interwoven in her lap – his fingers and thumb occasionally tapping the back of her hand along to the beat of whatever song is playing on the car stereo. To his credit, he’s remained remarkably calm throughout the entire four-and-a-half-hour drive. Looking sexy in his Ray-Bans, singing along to his favorite songs, playing air guitar along with the riffs and laughing when she accuses him of trying to cause an accident, making conversation when they pass by an interesting billboard, throwing out date ideas (which usually involve making out. “Think of all the possibilities, Case!”). It’s the polar opposite of how their drive on Friday had been.

(Was it only Friday that they weren’t speaking? How quickly things change.)

But the closer they get to home; the more Casey obsesses over the fact that they’ll be alone in their apartment. Just her and Derek, free to do whatever they want with no risk of anyone interrupting them. It’s a heady, intoxicating, terrifying prospect and Casey inadvertently clenches his hand a little tighter as they turn down their street.

Their apartment is exactly the same as it was when they left. Same white cabinets. Same red couch. Same framed daisy prints hanging above the small dining table that she’d picked up at a flea market downtown. And yet it feels like she’s looking at it with new eyes. This isn’t just Casey and Derek’s apartment anymore, now it’s the place where they live together. And to think, just a couple days ago she’d been shocked at Emily and Sheldon moving in together so quickly. The irony isn’t lost on her.

(If she ever works up the courage to tell Emily everything, she’s never going to hear the end of it.)

The sun is beginning to set in the distance over the lake, casting everything in a warm orange glow, and although it’s a little chilly from the crappy furnace in the basement that the landlord swears is new, Casey starts heating up the second Derek closes the front door behind him.

He drops their bags haphazardly on the floor while Casey carefully sets the Tupperwares down on the table. She wishes she knew the perfect thing to say or do right now. The silence isn’t exactly awkward, but it will be soon if she doesn’t come up with some topic of conversation, and so she blurts out the first thing she can think of just as Derek opens his mouth. Their words overlapping in a confusing mesh.

“Are you hungry?”

“God, fucking _finally.”_

There’s no time to process before he’s spinning her around and his mouth is on hers, and Casey promptly forgets that the leftovers need to be stored and organized in the fridge and that her clothes will become helplessly wrinkled if she doesn’t unpack soon. All that matters is the way his kisses taste like that citrus gum he favors, the way his hands are clutching at her hips like he never wants to let her go, the way he moans into her mouth when she buries her hand in his hair and tugs just a little too hard.

The table digs painfully into the back of her thighs, but she can’t be bothered to care when he slots his leg between hers and moves one of his hands around to grab her ass – gasping when he drags his lips across her jaw and down her neck, sucking a mark into the skin above her collarbone.

She feels helpless, but Casey McDonald is anything but, and so she shakes herself out of her Derek-induced stupor and tries to give as good as she gets – leaving one hand buried in his hair while using the other one to lift up his t-shirt and place her warm palm on the skin of his back, scratching lightly with her fingernails.

Derek groans and bites down on her shoulder, drawing a whimper from deep inside her body, before attempting to lift her onto the table. It rattles ominously, its cheap, flat pack design not suited for such vigorous use, and Casey immediately slides off it. The last thing either of them needs is an embarrassing hospital visit. “That isn’t going to work.”

“I have a better idea.” Derek grins and slides both his hands down to her thighs, encouraging her to jump up and wrap both her legs around him, but Casey just eyes him warily – her arms looped around his neck and resting loosely on his shoulders.

“You think you’re going to carry me somewhere?”

“Uh, duh.” Derek rolls his eyes affectionately. “Come on, hop up.”

“No way. That is how people end up hurt.”

“Are you saying you don’t think I can do it?” With a challenge in his voice, he grips her hips tighter and hoists her up all on his own – laughing when she squeals in surprise.

He stumbles across the living room, his hold on her somehow managing not to slip despite her squirming and the inherent awkwardness of walking while carrying another adult, then unceremoniously drops her onto the couch without any warning, covering her body with his own and capturing her complaints with his mouth.

“You are so –“ She gasps, humming with pleasure when he gives her another hickey underneath her ear and grabbing his face for a kiss to wipe off the self-satisfied smirk she finds there when he pulls back to view his handiwork. “- Frustrating!”

“You like frustrating,” Derek shoots back, his eyes dark and lips swollen from _her_ kisses. “Admit it.”

Heat shoots down her limbs and pools between her legs, and she swallows back the urge to tell him just how much. _One thing at a time, Casey_.

“Something must be seriously wrong with me.” She grabs the hem of his shirt and tugs, and Derek politely obliges by practically ripping it off over his head. What was it he’d said a moment ago? _God, fucking finally_.

He balls up his shirt and tosses it somewhere in the direction of the kitchen. “We knew that already.” Unabashedly half-naked, Derek settles in to keep kissing her, and while he works magic with his mouth Casey runs her hands over as much bare skin as she can reach – scratching down his back, tracing a line above his jeans, counting up his ribcage with her fingertips and grinning against his lips when he chokes out a strangled laugh and bats her hand away. “Stop that.”

“Ticklish, Der?” She teases, reaching for that spot again, and he squirms and grabs her wrist, tugging her arm up over her head so that she can’t keep torturing him.

“You’re playing with fire, Case.” The flash of warning in his eyes is her only notice before he lets go of her arm to brutally attack her armpit, and Casey shrieks and flails underneath him – unable to move away when he pins her down with his hips.

“Stop!” She cries, laughing so hard she can feel tears pooling in the corners of her eyes. “Stop, Derek, stop! I’m sorry!”

Thankfully, the second he gets his apology he withdraws his hand, and she’s left a gasping, breathless mess while he crows triumphantly. “Told ya to be careful. You know my spots, but I know yours.”

“Mutually assured destruction.” Casey’s chest heaves while her heart slowly stops pounding, and she rather likes the way it presses against Derek with every stuttered breath. Feeling daring, she widens her legs enough for him to be properly slotted between her hips, and he shallowly thrusts against her. There’s plenty of layers between them to consider their actions still relatively chaste, but her cheeks turn red, anyway. “Truce?”

He nods, then, slowly – giving her plenty of time to stop him – reaches for the buttons of her blouse. Undoing them one at a time, his eyes glancing back and forth between what his hand is doing and her face as if he’s half-expecting her to stop him. But stopping is the last thing on her mind.

The last button slips free, and Derek gently slides his hand underneath the loose fabric, thumb dipping into her bellybutton and making her inhale sharply, before dragging his palm up and up and _up._ Watching himself touch her as she’s bared inch by inch until the shirt falls away and he has full view of her lilac bra. It’s not her prettiest or fanciest (she’d been visiting her family home – of course she didn’t think she’d need to pack lingerie), but judging by the way his pupils are blown wide and how his tongue darts out to lick his lips, Derek doesn’t care that it’s plain.

His hand is warm through the padded fabric when it finally covers her breast, his thumb running over the edge at the top – barely tugging it down before releasing it – not doing much more than just holding her, and yet that somehow manages to drive her crazier than if he’d started squeezing and groping like the other guys she’s been with.

“Fuck,” He whispers, leaning down to press a kiss to the top of her left breast, then running his nose across her sternum to nudge the other side of her shirt out of the way and mirror the action on her right.

Derek covers her nipple with his mouth, sucking through the fabric, and Casey arches against him. It doesn’t seem possible, but somehow the wet spot he leaves behind is even more erotic than if he’d pulled the cup down and put his lips directly on her skin. Magnified by the way he makes eye contact with her when does it again, this time pressing his tongue against her as well.

“Derek,” She whimpers, clutching at the back of his neck and his shoulder to hold him in place.

“Yeah?” His voice is thick and heavy, and with a jolt Casey becomes aware of the way he’s grown hard against her center. That’s his… his _cock_. They could have sex. They’re _going_ to have sex.

She wants to, more than anything, but all it once it feels overwhelming.

Casey’s had her fair share of sexual experiences, maybe not as many as Derek (although he’s had less than he lets people think), but enough that she has a pretty good idea of what she likes and what she doesn’t. She’s polite, but not a prude, and doesn’t have any hang-ups about having sex with a partner she’s committed to. Her body, her choice. But sex with Derek means so much more than it ever has with anybody else.

Sensing her hesitancy, Derek presses one last kiss above her heart and lifts his head. “You know we don’t have to do anything, right?”

His voice is gentle and kind, something she thinks might only be for her, and it’s this more than anything else that reassures her.

“I want to,” She tells him, cupping his face and running her thumb back and forth across the faint scruff covering his jaw, “I’m just nervous.”

He nods and turns his head to kiss her palm. “We can take it slow.” He pushes off her and sits up, and Casey doesn’t even try not to stare at the obvious erection tenting his jeans. “Let’s just watch a movie or something. I think there’s some ice cream left in the freezer, if you want it. Or I can make popcorn.”

She is _not_ going to cry. She’s not. But Derek being sweet isn’t something she anticipated (which, in hindsight, she probably should have because he _can_ be sweet and she _knows_ that, she just… forgets between the banter and snark).

He's a good person, and Casey refuses to second-guess herself. For once, she just wants to act without needing a pros and cons list or a week-long debate in her head. And so, sucking in a deep breath and making a decision, she follows him all the way to where he’s sitting – already reaching for the controller – and straddles his lap.

“I don’t want to watch a movie.”

“No?” His hands land on her thighs, burning her through her jeans, and Casey scoots forward so that she’s pressed up as close to him as possible – not shying away when his erection presses against her center. “Hockey, then? There might be an old Leafs game on.”

“The only _stick_ I’m interested in, is yours.”

And that’s the moment when Casey realizes she really shouldn’t try to come up with clever innuendos, because Derek positively cackles – forcing her to scoot backwards when he bends over to clutch his stomach. “Ah,” He pauses to dramatically wipe his eyes, “There’s the Spacey we all know and love.”

Her heart clenches, and a slow smile spreads across her face despite her embarrassment. It’s not exactly an “I love you,” and she’s not sure she’s fully ready to say it back yet, even if it was, but still. _Still._ “Are you laughing at the girl sitting in your lap trying to initiate sex with you?” She raises her eyebrows, fixing him with a look. “Because she’s perfectly happy to leave and take care of things herself if you’re just going to mock her all night.”

To his credit, Derek immediately stops laughing and instead looks like she just clobbered him over the head – his eyes going glassy and his hands slipping underneath the edges of her still-loose shirt to stroke her hipbones. “That’s… not a bad idea.”

“What?” She frowns. Is he rejecting her?

“I mean…” He recovers himself quickly, and his slow, crooked smile is absolutely sinful. “You got to watch me, so it seems only fair that I get to watch you.”

Oh.

_Oh._

Casey’s positive she’s never turned such a dark shade of crimson before, and now she doesn’t have a shirt in the way to prevent Derek from following her blush as it spreads across her chest. “Der- _ek!_ ”

“Mmmm,” He captures her lips in a searing kiss, “Told you I like it when you say my name like that. Do you need me to show you how it’s done?” His fingers slide along the waistband of her jeans until he finds the button and flicks it open, his eyes daring her to tell him to stop.

She takes a second to think over what she wants, and in that time Derek slips the tips of his fingers into her underwear, but then she stops him with a hand on his forearm. “Not here. My room?”

Derek removes his hand and waits for her to climb off his lap before standing up. “You’ve probably washed your sheets more recently than I have.”

“Ew.” Casey scrunches up her nose and takes his hand, leading him down the hall towards her room. “That’s gross, Derek.”

“Hey! I wash them, I’m just not a neat freak like you. Hang on.” When they reach her door he lets go of her and jogs over to his room, disappearing inside for a few seconds before re-emerging with a handful of condoms. “I know how you feel about being prepared.”

She’s half-mortified that the thought didn’t even _occur_ to her, which is just further proof that she’s never been able to think straight with Derek in the room, but Casey brushes it off and smiles at him, grateful that he’d remembered. “Thanks.”

This will be her first time having sex in this bedroom, she realizes as she pushes the door open and steps inside. It just felt too weird, having guys over when Derek was sleeping in the next room, so she’d always packed a small overnight bag and slept over at her boyfriends’ apartments when the need arose. In a way she’s glad, though, because now it feels like she’s been saving it for the right person.

Derek moves past her like he belongs there and tosses the condoms on her nightstand. “You have way too many pillows.” He grabs the decorative ones, clearly about to throw them on the ground, and Casey hurries over to take them out of his hands before he somehow manages to cause damage.

“I like to be comfortable!”

“That’s great, but I don’t really want to be smothered to death while I’m inside you for the first time.” He points to her desk, ignorant of the way his blunt phrasing has left her speechless. “Can you put them over there?”

“I – um – yeah. Sure.” Casey does as requested while Derek kicks off his shoes and strips off his socks, wiggling his bare toes against her cute floral rug.

"Remember when you told me I should invest in a rug because the floors would be cold in the morning?” He looks up at her. “I’m beginning to think you were right. This is way better.”

Emboldened by the way he's blatantly checking her out, Casey shrugs off her shirt and tosses it into her laundry hamper before stepping out of her own shoes and socks, then crosses the room to stand in front of him. “Does that mean you’re going to give in and go buy one?”

He pretends to think about it, then shakes his head. “Nah, I think I’ll just sleep in here from now on. It’ll save me the cash.”

“Derek!” Casey protests, “You can’t steal my bed!”

Laughing, Derek winds his arms around her waist and draws her in close. “Not exactly what I meant, Case.”

“Oh.” She tilts her chin up to accept his kisses, before pulling away with a smirk of her own. “Does that mean you’re the one who wants to sleep with me, now?”

“Casey, Casey, Casey.” He punctuates each repeat of her name with a kiss along her jaw and down her throat. “I’ve wanted to sleep with you since I was fifteen.”

The admission is somehow both shocking, and not at all, and Casey grabs the back of his neck so that she can kiss him, running her tongue along his bottom lip until he grants her entrance. It should be illegal, to feel this good while kissing her stepbrother, and maybe it is in some provinces (she’s going to have to check on that) but she doesn’t care. All that matters is that they both have wanted this for a long time, and now they can finally have it.

Derek twists them around so that the back of her legs bump into the mattress, his hands going to the clasp of her bra. “Can I?” He gasps, slipping his fingers underneath the elastic band and massaging her muscles in small circles.

“Yes.” Casey holds her arms up in front of her chest while he undoes the hook, waiting until her bra loosens before slowly lowering her arms and letting it fall to the floor between them, revealing herself to his hungry gaze.

“You know, Case,” He says conversationally, Adam’s apple bobbing, “I’ve always thought we should have a nudity clause in our apartment contract.”

She laughs, the sound turning into a moan when he cups her breasts and traces patterns with his thumbs. Her skin breaking out in goosebumps and prickling pleasantly from the featherlight pressure. “Oh yeah? What kind of clause.”

“One that says you should always be naked when we’re home.” He lowers his head to take one of her nipples in his mouth, drawing it to a peak and pressing it to the roof of his mouth with his tongue, and Casey nearly falls over. Her breasts have always been sensitive, but in an average sort of way. Something that feels good, but isn’t _mindblowing_. That is, until Derek. Is it just his technique, or is it because she wants him so badly? Either way, Casey’s never been this aroused in her life.

She barely manages to keep track of the conversation enough to tease him. “Only when we’re alone, I hope.”

He nips at her, making her jump, his voice dropping. “Obviously.”

The way he says it, all low and possessive, makes her squirm, and Casey drags her hands down his chest – making sure to scrape his nipples in retaliation and smiling when he whimpers – and across his abs before popping the button on his jeans and shoving them down to his knees. “Only if you’re going to be naked, too.”

Derek gives her a look as if to say, _well, duh_ , and bends over to finish removing his jeans – kicking them to the side when he’s done and reaching for hers. And Casey lets him pull them all the way down her legs until he’s squatting in front of her, holding first one leg, then the other while she steps out of them.

He kisses the inside of her right knee, then her left, but before he can trail his lips up higher she stops him with a thought. “Hang on – we can’t hang out naked. Think of the germs. That wouldn’t be sanitary at all.”

His head thunks against her thighs and he huffs out a disbelieving laugh, warm breath hitting her knees. “Casey, please don’t ruin the mood. I’m _trying_ to turn you on.”

“Right.” She winces and strokes his head in apology. “Sorry. You know how my brain is.”

“I promise we can discuss this as much as you want _after_ I give you at least two orgasms. Maybe three. Deal?”

“That seems a little optimisTIC-gah!” Casey’s arms flail behind her, barely catching her in time when Derek abruptly stands and pushes her backwards onto the mattress – bouncing a little when she lands and glaring at him. “What was that for?”

He grins entirely without remorse while she fumbles with the blankets, pushing the red and pink duvet down to the end of the bed where it’ll hopefully be safe. “It was an accident.”

“Accident my ass,” Casey mutters, folding her arms and pulling a face at him as he climbs over her, knocking her legs apart with his knees.

“Yep.” Derek drops, resting his full weight on her and taking her breast in his mouth again, bringing his left hand up to play with the other one while his right trails lower to trace the outline of her underwear where it meets her thigh, and Casey forgets why she was pretending to be annoyed.

He feels even more erect, if that’s possible, and Casey wonders mutely if all this time their bickering was just extended foreplay.

She bucks her hips and Derek grinds against her with a groan, sucking the underside of her breast until there’s a mark there to match the ones on her neck before peppering kisses down her abdomen – licking a line above her underwear.

“This is gonna be number one,” He promises, placing a wet kiss underneath her bellybutton while looping his hands in her underwear and tugging them down far enough that she can pull her ankles out and kick the fabric free.

“I like your confidence.”

“Only when it’s about to benefit you.” He tickles the bottom of her foot and she kicks his leg, making him laugh. “I seem to remember a lot of complaints about my ego over the years.”

“Well maybe if you weren’t so annoying about it.” She gasps when his palms drag up the insides of her thighs, spreading her legs far apart and raking his eyes down her body before zeroing in on her center (her brain whisper-thinks the words pussy and cunt, and she wonders with a clench what it would be like to hear Derek say them someday) - making her feel somehow both lewd and eager all at once. His lips follow the path left behind by his hands, warm and wet, and Casey blurts out, “Are you going to give me a hickey, there, too?”

He pauses, mouth pressed to the inside of her thigh, just inches from where she wants it most, and she can feel his lips spreading into a smile. “Do you want me to? I kind of thought you were going to yell at me after the first one.”

“I’m not _thrilled_ about having to cover those up, but uh, I don’t mind when it’s hidden.” Which is strange, because she really doesn’t mind and normally Casey _hates_ hickeys. But something about the possessiveness in his voice earlier and the way he’s looking at her now makes her want it. Want that proof in the morning that this is real – that he is hers and she is his.

“Noted.” Derek cups her knee to hold her leg flat against the mattress and nips at her before working another purple mark into her pale skin. Pulling back to gently kiss it when he’s done. “It’ll be our secret.”

_God_. Casey flushes, impossibly wet at this point and ready to grab him by the ears and haul him up so that he can sink into her – his plans be damned – but Derek turns his head and licks a stripe through her folds and she realizes what an incredibly _stupid_ plan that would have been.

“Fuck!” The curse slips from her lips by accident, and Derek hums against her – obviously pleased with himself.

“Language, princess.”

He dives in with gusto after that, obliterating whatever strangled retort she might have tried to come up with. Alternating between broad strokes with his tongue and sucking on her clit, drawing noises from her she didn’t even know she was capable of making – her hands clutching uselessly at the sheets as she practically bucks into his face.

Derek throws an arm over her hips to save himself from a broken nose, holding her down while he drops his head a little lower to trace around her entrance with his tongue, and Casey feels like dying in the best way.

“Der,” She moans, barely managing the single syllable.

“Yeah?”

“Can you – guh – fingers – _please_.” She’s never going to hear the end of it. He’ll be teasing her about the begging until the end of time. But it works, and he takes her clit in his mouth again as he works two fingers into her at once.

She’s wet enough that she takes them easily, but is wholly unprepared when Derek curls them inside her just as he sucks particularly hard and flicks her clit with his tongue, and with a shout she comes harder than she ever has before – her thoughts replaced by blinding white stars and her body curling around his head.

He works her through it, pumping his fingers while her orgasm rocks through her, and it feels like forever before she’s able to collapse back into the mattress. When she does, she realizes she can feel his tongue at her entrance – lapping up her wetness around his own fingers – and she nearly comes again on the spot.

“Why,” She gasps breathlessly, “Do you have to be so good at that?”

Derek’s head perks up, his hair a tangled nest after the way she’d helplessly grabbed at it a second ago, his mouth and chin shiny and wet, and he grins. “I _told_ you so.”

Slowly feeling more like herself, Casey _does_ grab his ears then and tug him up above her. “Did you take notes while watching all that porn?”

“Please,” He scoffs, removing his boxers and kicking them to the bottom of the bed, “I don’t need help to know what I want to do to you.”

Ugh. Well now she just has to kiss him again.

He comes to her willingly, unashamed of the remnants of her orgasm on his lips, and Casey is surprised to find she’s not disgusted by the taste, either. It’s kind of hot, actually, and she opens up further while reaching between them to finally get her own hand on his dick.

Derek grunts and hisses when she wraps her fingers around him, covering her hand with his own. “Not so tight, Case. Too sensitive.”

“Sorry.” She frowns, disappointed in herself for getting it wrong after he’d just treated her so spectacularly. “Show me how you like it.”

“Don’t be sorry.” He captures her with another searing kiss. “Fuck, don’t be, okay? It feels amazing and I’ll show you whatever you want.” He buries his head in the crook of her neck when she remembers that twisting motion she’d seen him do last week, hips jerking against her. “I promise. But I’m not gonna last if you don’t stop.”

“Okay.” She twists her hand again before releasing him, and Derek nips at the mark on her collarbone.

He reaches for one of the condoms, tearing it open and letting the wrapper get lost in the sheets (Casey the certified Neat Freak tries very hard not to remind him there’s a perfectly good garbage bin by her nightstand – she doesn’t want to become Casey the Moodkiller) and rolls it over his erection before settling back in between her legs.

“You ready?” He asks, brushing some of her hair back from her face, and Casey leans up to tenderly press her lips against his, lingering there and soaking in the moment before nodding.

Derek lines himself up and hitches one of her legs around his waist, before slowly pushing into her. She imagines the pace is for her benefit, but what it really does is ensure she feels every single centimeter of him moving inside her cunt ( _there_ , she said it). It makes him feel huge, and she already knew from looking that he was slightly above average, and Casey can hardly catch her breath.

“Nng-Case-you with me?” He readjusts his grip on her thigh, opening her up more until she thinks there can’t possibly be any more to take, and she turns her head to blindly find his lips with hers, scrambling to find his free hand so she can tangle their fingers together. Needing to complete the connection.

“Yes,” She pants, arching her hips to encourage him to start moving, and Derek groans. “ _Yes.”_

She knows he tries to start slow, but after the first few thrusts it’s obvious that slow isn’t in the cards for them this time. It’s been too long. Been built up too much. And Derek’s hips start pistoning against hers with a pace that has sweat pooling between their bodies and the most filthy sounds coming out of their mouths.

“ _Derek_ ,” She moans his name again and again, the heat already building inside her – ready to combust a second time. Her body feels electric, like all her nerve-endings are attuned to him and sparking with every touch. It’s _addicting_ , and she’s suddenly worried she’s never going to want to do anything other than this ever again. Casey McDonald, notorious neurotic neat freak and keener, the sex addict. Who would have thought?

“So good, Case,” Derek groans, as if echoing her thoughts, “You’re fucking amazing. So fucking gorgeous. So perfect.” And then it’s Casey’s turn to preen, always eager for positive feedback. “Touch yourself,” He commands, managing to lock eyes with her and holding her complete focus, “Like we talked about earlier. Wanna see it.”

“Yeah?” She asks, feeling an inexplicable twinge of shyness despite the fact that he’s _literally_ fucking her right now, and Derek takes their intertwined hands and slips them between their bodies until both their fingers are pressed against her clit – taking a second to feel himself entering her on his next thrust before letting go – and her walls flutter and clench around him. “Okay.”

He manages to prop himself up just enough to watch what she’s doing, and Casey decides shyness is overrated. She knows what she likes and immediately starts rubbing her clit in sync with his thrusts.

Knowing he’s getting off on watching her is almost more arousing than what their bodies are doing, and Casey soars up and over her peak as Derek’s mouth crashes into hers in the sloppiest, hottest kiss of her life – his own orgasm following close behind.

His whole body shudders with his release before collapsing, and they both lay there in a sweaty mess of limbs – happy and sated and basking in the aftermath. Derek buries his face into her neck and she brushes her fingers through his hair, content to hold him with her body while they both recover.

Eventually he softens and needs to pull out to dispose of the condom, and she’s grateful at least now he remembers the waste bin because even in her orgasmic bliss she’s still capable of shouting at him for being gross. She’s a multi-tasker like that.

“I think,” He starts, rolling back over so that he’s lying right next to her and grabbing her hand, “We should add another clause. Nudity plus sex. Daily.”

Casey laughs, light and free, and turns to prop her chin up on his shoulder. “Don’t you think you’d get worn out having sex _every_ day?”

“No.” Comes his immediate response, and he ducks his head to kiss her. “I don’t. But I’m willing to test that theory with you.”

“But what about school and hockey and our friends and –“

“And I don’t give a flying fuck about any of that.” He grabs her by the waist and rolls her on top of him, earning a surprised snort of laughter when he accidentally tickles her in the process, and tilts his head down to kiss her nose. “All I want is in this room.”

Apparently post-sex Derek isn’t as afraid of feelings as pre-sex Derek, a precious observation Casey files away, and she tucks her arms underneath his back and rests her head underneath his chin. “Your record collection isn’t in here,” She reminds him to save herself from getting too emotional, certain he can hear how much his words mean to her in her wavering voice, and Derek chuckles while tucking a strand of hair behind her ear.

“Damn. Okay, this room and my room.”

His stomach rumbles, and she grins. “And we don’t have any food in here.”

Derek trails his fingers down her spine to the top of her ass, gripping it with both hands while grinding against her pussy. “Guess I’ll have to find something else to eat.”

“Derek!” She squirms, blushing as if that isn’t exactly what he was doing earlier, and he wraps his arms around her to steamroll over so that she’s underneath him again. He’s laughing at her, face full of joy and eyes full of an emotion she knows mirrors her own, and she smiles. “So… three, huh?”

His laughter fades into a slow smirk and he nods. “Definitely. Shower?”

“Absolutely.” She grins and takes his hand, following him off the bed and into their future.

Together. 

**Notes for the Chapter:**

> This has been a lot of fun to write and I'm really going to miss it. <3
> 
> Thank you for reading!


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